NEED HELP- AR10 ISSUES

[357magag]

Sick and Tired of sneaking up on hawgs and getting 1 shot. Happened again tonight.
My 9yr old son felt so bad for me he offered to let me shoot his AR pistol.

Who or what company is an expert AR Gunsmith that I can send my AR10 to make it run like a sewing machine?

It doesn't want to feed smoothly
Scratches up the brass upon feeding
Doesn't want to lock up bolt in the chamber without it being oiled to heck.

*have magpul and lancer mags

Have a ton of money tied up in AR10 6.5CM Build.
Mega Matched Receiver Set
BSF CF 16.5"
JP Silent Spring
Trigger Tech Diamond
JP LMOS BCG
Ti misc parts
Superlative Arms adjustable gas block
Wilson Combat handguard

 

[Quietguy88]

You need a heavy carrier, most likely. No experience with that barrel.

So, i hope it is a rifle length gas system. Next, I hate jp's scs. I use sprinco red spring, kynshot buffer and a forward controls design(fcd) 9 position a5 receiver extension. Mind you the buffer is 3.25" compressed and is valved for large frame rifles.

I also use a sup arms gas block. They are the best. Follow the instructions. Turn the adjustment screw until it is entirely inside the gasblock. Clockwise. Count 18 clicks counter clockwise. From there, keep turning it counter clockwise until you fail to lock open on the bolt catch. Turn it two or three clicks back in.

Now, what bullets are you using? Vld, uvld types.. the long pointies.. have issues. They tend to be so skinny and long that they go inbetween the barrel extension feed ramps and slam into the forcing cone on barrel itself. This usually damages the projectile, cases lackluster accuracy and in a plethora of instances has locked guns up.

I will not insult JP and call them the hornady/trijicon/Q of the firearms world.. all marketing, no delivery; JP products are good.. but for a fuck less money, you can get equally good parts.

Now, I have had nothing but problems with lightened carriers in large frame ar's. 308, 6.5creed.. any chambering. The guns just need heavy mass. Using muzzle device and tuning gas with buffer spring is your best bet.

By heavy mass I mean a 5oz buffer and a full weight bcg. Minimum. I have used a 10oz rifle buffer.. however, I much prefer the 5oz hydraulic and tuned gas. Especially having a 9position receiver extension. Bcm's compartment buttpiece works great for an all around rifle. Will fully collapse with no issues, fits very snug and good cheek weld. Beats the hell out of a magpul moe rifle any day. The prs stock.. unless you got big optics and are laying prone 125% of the time - no way.

Am done plugging my personal choice of equipments..

------

This said, moving to your problem - if the feed ramps and the barrel extension lugs at 2oclock to 4oclock were not chamfered/buffed properly it will chew up brass. Probably has scratches on a chambered and removed live round's projectile too. Which, doing this a few times from a fully retracted bolt.. pull charge handle completely rearward and let it slam a live round into chamber. Do four or five this way. Look at the tips of bullet and around the ogive.. is good indication if your projectiles ought be changed.

Meaning, if you got deformed tips and scratches on bullet around the neck, not the curve of bullet.. find something more round, less pointy long. You will almost certainly have scratches on the bullet, unless things are super radiused and smooth. Same for the sidewalls of brass. Ar's do that. A good tumbling will usually erase the marks from brass.

Feeding can be spring alongside gas related. Not enough buffer spring, with too heavy mag spring or extractor/ejector spring.. can choke. Likewise, not enough gas and it will not have enough rebound energy sending the carrier forward and.. she chokes.

Did you verify the carrier travels the proper distance into buffer tube? First, is it a 7" internal depth, 7.75" or a rifle tube? Short stroking or having the gas key of carrier peen into the buffer tube can make big issues?

The bolt not wanting to shut - did you verify headspace? How does the chamber look? Burrs, chatter? I assume the bolt glides smoothly into battery on empty chamber, so..

Does the gas tube extend half of the cam pin's cutout? Look in the upper receiver with the bcg removed. The gas tube should terminate roughly dead center of the cam pin slot in upper receiver. The slot where the cam pin rotates when bolt is completely seated in battery.

--------

It sounds like a lot, but it really is only a few minutes of looking if you know what to look for.

Please clearly explain the malfunction? When does it happen, what seems to cause it.

 

[Earnhardt]

Here’s my go to for large frame ARs
Heavy buffer…9-10oz.
Full mass BCG
Tubbs Flatwire
Adjustable gas block

 

[XP1K]

I've been going round and round with a PWS large frame in 308.

Went to an A5 tube from LMT, a Tubbs flatware spring and made my own custom buffer that came in around 11.5oz. Runs good now.

Had problem similar to the OP. I'd get 1-3 shots and then click. Rack it and bang, 1-3 more. Best I could tell it was bouncing put of battery enough to still let the hammer drop but cause a light primer strike.

Heavy buffer and a spring with the A5 tube fixed it.

 

[bigjake83]

Sick and Tired of sneaking up on hawgs and getting 1 shot. Happened again tonight.
My 9yr old son felt so bad for me he offered to let me shoot his AR pistol.

Who or what company is an expert AR Gunsmith that I can send my AR10 to make it run like a sewing machine?

It doesn't want to feed smoothly
Scratches up the brass upon feeding
Doesn't want to lock up bolt in the chamber without it being oiled to heck.

*have magpul and lancer mags

Have a ton of money tied up in AR10 6.5CM Build.
Mega Matched Receiver Set
BSF CF 16.5"
JP Silent Spring
Trigger Tech Diamond
JP LMOS BCG
Ti misc parts
Superlative Arms adjustable gas block
Wilson Combat handguard

You need to shitcan that barrel, all your other parts are fine but as others have said I'd get a full mass carrier. Sell the barrel and replace it with a Proof SS 18" .308 .. Wilson combat also makes a decent barrel and so does Rainer arms ultra match.

 

[sinister]

Who or what company is an expert AR Gunsmith that I can send my AR10 to make it run like a sewing machine?

It doesn't want to feed smoothly
Scratches up the brass upon feeding
Doesn't want to lock up bolt in the chamber without it being oiled to heck.

*have magpul and lancer mags

Have a ton of money tied up in AR10 6.5CM Build.
Mega Matched Receiver Set
BSF CF 16.5"
JP Silent Spring
Trigger Tech Diamond
JP LMOS BCG
Ti misc parts
Superlative Arms adjustable gas block
Wilson Combat handguard

Who built it? Send it back and have him make it right.

It's a rifle. People have been shooting medium-caliber semi-automatic AR rifles for at least 30 years.

 

[Earnhardt]

You need to shitcan that barrel, all your other parts are fine but as others have said I'd get a full mass carrier. Sell the barrel and replace it with a Proof SS 18" .308 .. Wilson combat also makes a decent barrel and so does Rainer arms ultra match.

What…no love for the 6.5 CM BSF barrel?….

 

[bigjake83]

SOLD - Craddock 16” 6.5 creed AR10 barrel

Never fired. 6.5 creed 16” barrel, rifle length gas system, .875 gas block, cut from a barlein blank. Threaded 5/8-24 bead blast finish (medium heavy contour) Was $600 NOW $500 shipped conus. Ships same day! I am faster than amazon PayPal/ Venmo preferred

www.snipershide.com

 

[GUNNER10]

Sick and Tired of sneaking up on hawgs and getting 1 shot. Happened again tonight.
My 9yr old son felt so bad for me he offered to let me shoot his AR pistol.

Who or what company is an expert AR Gunsmith that I can send my AR10 to make it run like a sewing machine?

It doesn't want to feed smoothly
Scratches up the brass upon feeding
Doesn't want to lock up bolt in the chamber without it being oiled to heck.

*have magpul and lancer mags

Have a ton of money tied up in AR10 6.5CM Build.
Mega Matched Receiver Set
BSF CF 16.5"
JP Silent Spring
Trigger Tech Diamond
JP LMOS BCG
Ti misc parts
Superlative Arms adjustable gas block
Wilson Combat handguard

I don't want to come across as harsh but you have a parts gun that runs like a parts gun. Tolerance stacking in AR15's is a thing and in 308 AR's an even bigger thing.

Does this mean one can't build a really good large frame AR, absolutely not, but considering all the factory options out there, the question becomes why...

Considering its probably going to be around a grand to figure out whats going, I would considering parting it out and picking up a factory gun and be done with it as you are already approaching LMT, Noveske and LWRC money. Hell it would probably be cheaper to buy a marked up Hk MR762

 

[Quietguy88]

I don't want to come across as harsh but you have a parts gun that runs like a parts gun. Tolerance stacking in AR15's is a thing and in 308 AR's an even bigger thing.

Does this mean one can't build a really good large frame AR, absolutely not, but considering all the factory options out there, the question becomes why...

Considering its probably going to be around a grand to figure out whats going, I would considering parting it out and picking up a factory gun and be done with it as you are already approaching LMT, Noveske and LWRC money. Hell it would probably be cheaper to buy a marked up Hk MR762

Hey man, he has damned good parts. Mega is top dick in the receiver world. His JP bolt is about the standard. Most likely, if everything is within acceptable tolerance.. he probably just needs a different carrier and buffer.

What I am saying is - he is not on the shit end of 'parts build' by any measure. For price of those weapons you recommend.. he can fix his for a few bucks.

Honestly, I got a blemished rubber city bcg for sub $200. It was 'blem' because a chrome firing pin, not a nitrided firing pin. Which are consumables anyways.. using their bcg and the mcfarland single piece gas ring.. I have JP bcg's. Never buying one again. Twice the cost, hardly anything better. A candyshell dlc coating and a bunch of pretty cnc engraved initials.

For sub $500 he most certainly could fix his setup. Forward control design re5(the 9position a5 receiver extension), a sprinco red spring, kynshot buffer, end plate, bcm buttstock and a new carrier.

Of which, he can sell the jp lmos carrier and almost wash his expense.

Mind you, that is if he has no mismatched parts. Gastube is proper length, chamber is in spec.

He could go cheaper and use an h3 or h4 ar15 carbine buffer. A 3.25" long buffer. Again, sprinco red spring and the a5 buffer tube. Ar308 needs 7.75" buffer tube internal depth to use standard 'milspec' ar15 buffers. If using a milspec 7" buffer tube, ar308 needs a 2.50" buffer.

Putting the simple numbers for others, not intended as insult.

Best luck to the OP

 

[Quietguy88]

I've been going round and round with a PWS large frame in 308.

Went to an A5 tube from LMT, a Tubbs flatware spring and made my own custom buffer that came in around 11.5oz. Runs good now.

Had problem similar to the OP. I'd get 1-3 shots and then click. Rack it and bang, 1-3 more. Best I could tell it was bouncing put of battery enough to still let the hammer drop but cause a light primer strike.

Heavy buffer and a spring with the A5 tube fixed it.

11.5oz? Dear lord.. did you grind a block of tungsten down???

Humor aside - how does that thing feel?

 

[XP1K]

11.5oz? Dear lord.. did you grind a block of tungsten down???

Humor aside - how does that thing feel?

Recoil wise ? It actually feels really good. I think the Tubbs spring had the biggest effect on overall feel.

Initially I had tried the car-XH from heavybuffers.com with their heavy spring. Kicked like a mule and it was a sharp recoil impulse. Was no fun to shoot. Spring change smoothed it out. Spring, A5 tube and a mondo buffer made a pretty nice combo.

Definitely a full mass setup lol.

I cannibalized my car-xh and my factory buffer for the weights and tge rubber plug.

 

[bfoosh006]

Sick and Tired of sneaking up on hawgs and getting 1 shot. Happened again tonight. What ammo are you using ? Reloads ? Factory ammo ?
My 9yr old son felt so bad for me he offered to let me shoot his AR pistol.

Who or what company is an expert AR Gunsmith that I can send my AR10 to make it run like a sewing machine?

It doesn't want to feed smoothly
Scratches up the brass upon feeding ........... Pics of the fired cases ?
Doesn't want to lock up bolt in the chamber without it being oiled to heck.

*have magpul and lancer mags FWIW... Lancers have a very stiff spring , enough so, that I have seen them slow feeding enough to cause feeding failures to feed in some "builds".

Have a ton of money tied up in AR10 6.5CM Build. ........ How many rounds have been fired through your rifle ?
Mega Matched Receiver Set
BSF CF 16.5" ............. Tight Chamber ? Are the feed ramps polished ? Photo of the feed ramps ?
JP Silent Spring ............... what weights ?
Trigger Tech Diamond
JP LMOS BCG
Ti misc parts
Superlative Arms adjustable gas block ............... what setting are you using ?
Wilson Combat handguard

Expand the quote to see the questions.

 

[rpoL98]

did you deburr and polish the feed ramps, and also knock off the sharp edges of the barrel extension lugs at 3 o'clock? that's where the scratches are occurring to your brass. AFAIK, no barrel mfr does this that i've seen, but then, I haven't bought a $1,000 barrel yet. But it sounds like that's what you need to do if you want your brass unscratched. Also, if you're using metal mags, smooth out the sharp edges of the as-stamped feed lips.

 

[Quietguy88]

did you deburr and polish the feed ramps, and also knock off the sharp edges of the barrel extension lugs at 3 o'clock? that's where the scratches are occurring to your brass. AFAIK, no barrel mfr does this that i've seen, but then, I haven't bought a $1,000 barrel yet. But it sounds like that's what you need to do if you want your brass unscratched. Also, if you're using metal mags, smooth out the sharp edges of the as-stamped feed lips.

Very good start right here.

 

[Quietguy88]

Recoil wise ? It actually feels really good. I think the Tubbs spring had the biggest effect on overall feel.

Initially I had tried the car-XH from heavybuffers.com with their heavy spring. Kicked like a mule and it was a sharp recoil impulse. Was no fun to shoot. Spring change smoothed it out. Spring, A5 tube and a mondo buffer made a pretty nice combo.

Definitely a full mass setup lol.

View attachment 7938374View attachment 7938375View attachment 7938376View attachment 7938377View attachment 7938378
I cannibalized my car-xh and my factory buffer for the weights and tge rubber plug.

Is that last picture showing an extension that nests inside the bcg?

I have always wondered about the tubbs flatwire.

I used the 10oz rifle buffer from slash and the included spring. I changed, went to a5 tube and the kynshot. Forget which model number. It changed the feel. I had thought about trying the flatwire, but went with the sprinco red. Suppose one day I will spend the $20 on a flatwire.

That buffer is definitely huge. I bet the forward reset really pushes the muzzle down.

 

[mtrmn]

If your gun doesn't have at least 3-400 rds through it it ain't even broke in good. You mentioned it had to be oiled to run at all. Large frame ARs are like that. The BCG needs to be dripping with oil during the breakin period.
That and a heavy buffer/spring in the proper tube. A FULL MASS carrier and buffer weight of AT LEAST 5.5 ounces (for 308, don't know about the 6.5) All that low-mass shit is best to add to a known-good-running gun that has already been de-bugged. If you start out with all these high-end parts (in a gun that may not be broken in at that) and have trouble then there's so many variables and possibilities that could cause trouble that you don't have a clue which way to go.

 

[Quietguy88]

OP, my dad has a 6.5creed with the JP bolt. Even then it has ejector smears. Using a 22" criterion barrel, rifle gas and sup arms gasblock. Nothing really makes the smears go away. Using factory ammo of various kinds. Hornady, berger, does not matter.

Honestly, it needs a longer gas system. Using a full mass carrier, 5oz hydraulic buffer and a red spring. I am tempted to change from the red to orange spring, hoping to slow it down. However even reducing the gas enough that it will not lock open on empty, it still has ejector smears/swipes. I suspect that it needs a heavier buffer. Which means I am likely to machine a carrier weight and possibly switch to the orange spring.

Sharing this, because it may offer insight.

The polished up magazines is good guidance. That is a whole other subject. I have a handful of first gen ASC mags. They have a feed ramp that protects the upper receiver stamped into the body. It matches the barrel extension contour and masks the area of upper receiver where m4 feedramps are found. The magazines are very roughly stamped. I disassembled them, polished the feed lips, the stamped in feed ramp and then the rear of magazine where the bolt stop sits. There was a sharp lip around that protrusion which was chewing the magazine well up.

Lastly, leave the magazines fully loaded for a month.. or three. Seriously, out of the bag they hold 19 rounds. When loaded with hammer and shoe horn.

For elbow grease and catching them on sale for $15/ea.. it is worth the work. They hold roughly 2.85" coal. I think I could stretch them closer to 2.88" coal, but for reliability reasons.

Now, if you go about polishing your own barrel extension.. stuff a rag or something down the barrel before starting. Use hobby files, maybe even diamond files to begin breaking the edge. Felt bobs with a dremel and green jewler's rouge will smooth everything without removing material. Just break the sharp edges and then mirror shine everything. Do not 'remove' any metal. You want no sharp edges to catch a fingernail, with it feeling like glass beneath your fingernail on all surfaces that the brass or bullet touch. Again, you DO NOT want to change the shape of the metal.

All the polishing is moot if the bullet is slamming into the barrel forcing cone before the brass runs up the barrel extension feed ramp.

There is a wealth of knowledge shared here. A lot of experience is being offered by all the other posters. Hopefully you can get everything up and running silky smooth with some basic diagnostics. It seems like you just need more reciprocating weight. Especially if the gun runs fine for a few rounds. So long it ejects proper, the chamber passes the plunk test, bolt to chamber tolerance is providing proper headspace and you have proper travel of the bcg from battery to full compression of buffer spring. Gas tube not preventing full battery and buffer is proper length for receiver extension, preventing impact to lower receiver by gas key or the bcg is short stroking.

If nothing that is discussed in the previous paragraph is happening.. i would start with increasing bcg and buffer weight. First the bcg, then the buffer. My personal experiences show the 6.5creed needs more weight than the 308. I suspect due to higher chamber pressures and longer dwell of said pressure.

Keep us posted. Best luck.

 

[GUNNER10]

Hey man, he has damned good parts. Mega is top dick in the receiver world. His JP bolt is about the standard. Most likely, if everything is within acceptable tolerance.. he probably just needs a different carrier and buffer.

What I am saying is - he is not on the shit end of 'parts build' by any measure. For price of those weapons you recommend.. he can fix his for a few bucks.

Honestly, I got a blemished rubber city bcg for sub $200. It was 'blem' because a chrome firing pin, not a nitrided firing pin. Which are consumables anyways.. using their bcg and the mcfarland single piece gas ring.. I have JP bcg's. Never buying one again. Twice the cost, hardly anything better. A candyshell dlc coating and a bunch of pretty cnc engraved initials.

For sub $500 he most certainly could fix his setup. Forward control design re5(the 9position a5 receiver extension), a sprinco red spring, kynshot buffer, end plate, bcm buttstock and a new carrier.

Of which, he can sell the jp lmos carrier and almost wash his expense.

Mind you, that is if he has no mismatched parts. Gastube is proper length, chamber is in spec.

He could go cheaper and use an h3 or h4 ar15 carbine buffer. A 3.25" long buffer. Again, sprinco red spring and the a5 buffer tube. Ar308 needs 7.75" buffer tube internal depth to use standard 'milspec' ar15 buffers. If using a milspec 7" buffer tube, ar308 needs a 2.50" buffer.

Putting the simple numbers for others, not intended as insult.

Best luck to the OP

Its all good,

What I am saying is that while your not wrong about any of that stuff, there are a lot of "ifs" in the equitation that take time,energy and money to unfuck, that the op sorta of indicates that he wants to pay somebody to address. 500 bucks might address the issue, might not...

I've built Large Frame AR's and would have no issues troubleshooting this stuff BUT, its really not worth the time. Just grab go to euro optics, add the a DD5 in 6.5cm to cart, and be done with the matter by the end of the week.

 

[mtrmn]

I honestly don't know much about the JP LMOS, so I went to their website and checked it out. They clearly state that it will speed up bolt travel, which IN MY EXPERIENCE is the exact opposite thing you'd want to do in this situation. So, like so many have suggested, the first thing I'd do would be to replace the BCG with plain ol' full mass BCG and go from there. Start with what we KNOW will work.

May I suggest:

- Toolcraft AR-10 / 308 / 6.5 Creedmoor Bolt Carrier Group - Black Nitride - AR15Discounts

Find the Best BCGs for AR-15, AR-9 and AR-10 / LR-308 for your next build. 80+ BCGs from top Brands at best prices & backed by our satisfaction guarantee.

ar15discounts.com

ETA: I was told a long time ago "The more "high performance " parts you bolt on the family sedan, the less reliable it becomes."

 

[sinister]

Retired Marine Gunner Dennis DeMille specifically designed 6.5 Creedmoor for the AR-10 for Camp Perry -- with a rifle length gas tube.

6.5 Creedmoor typically operates in the 58,000 - 60/62,000 (SAAMI) PSI chamber pressure range -- higher than 7.62 in chamber and at the gas port.

 

[Jsp556]

Full mass carriers and the Armalite carbine set-up (or a copy of) has worked on every large frame I’ve ever dealt with. Sometimes the most simple solution is the best.

 

[Quietguy88]

Call rca and ask about this:

*BLEM* Standard Mass AR-10 .308 Win+ Multi HP Calibers DPMS complete W/ Assist - Welcome to Rubber City Armory

This is a COSMETIC BLEMISHED complete DPMS style BCG with Blacknitride+ finish - PLEASE NOTE - ITEM MAY HAVE IMPERFECT LASER ENGRAVING, OR COSMETIC IMPERFECTIONS BUT IS OPERATIONALLY CORRECT. ALL RCA WARRANTIES STILL APPLY. PLEASE NOTATE IN THE ORDER NOTES IF YOU WISH YOUR CARRIER TO BE...

rubbercityarmory.com

The toolcraft model is best had with the high pressure bolt. It is $10 less than the rca and rca is glassy smooth. While at it, spend the extra few dollars and get their mcfarland single gas ring.

That all said - the mirror polished nitride bcg is slick.

Otherwise, I have had issues with rifle length gas and 6.5creedmoor personally. As described above. I would never recommend rifle length gas again. At minimum it must be a +1 rifle gas system. They just run too much pressure. Especially when loading anything over 130gr. Slow powder, small bore. Big pressure makes fast unlock.

Just because the case web is not ballooning and primers are not popping does not indicate acceptable.

Frankly, I would not go the route of 6.5needsmore after my experiences. However, we are getting off the facts and into the personal opinion weeds with those statements.

On the subject of buying a daniel defense.. DD got nothing on mega. The OP already has one of the best platforms for a large frame rifle. No sense on pulling out and taking losses. Just pawn that garbagio carrier on an idiot and get cheaper, better parts. Fix the gun and be happy.

 

[357magag]

I also have tried the KAK 6.5CM complete BCG it jammed.

So basically I need to ditch the JP SCS and JP LMOS bolt.
Full Mass Bolt (we wouldnt the KAK work?
Get a normal spring setup.

 

[Quietguy88]

I also have tried the KAK 6.5CM complete BCG it jammed.

So basically I need to ditch the JP SCS and JP LMOS bolt.
Full Mass Bolt (we wouldnt the KAK work?
Get a normal spring setup.

What do you mean jam?

Is the brass getting pinched inbetween the bolt and against the feed ramp? Is the bolt pushing against the headstamp and the bullet is crushed against the barrel or halfway into the chamber?

I already asked about which bullet you are using. The VLD and UVLD bullets are not happy with the AR. They tend to miss the barrel extension feed ramp and cause this issue.

Once more - i dislike the jp products. They are tinker toys that cost too much and perform too little. If you run a single ammo that is tuned with all the other parts, it is great. Otherwise, it is just too much trouble for me.

You need all three tungsten weights on the scs. I do not know which spring it will take. Plus a full mass bcg. Just to start.

Then, I suggest using the 130gr berger hybrid or some bullet with a tangent ogive. Those secant types are so narrow they have issues.

More clearly defined malfunctions after checking the few areas is needed.

 

[Quietguy88]

If your bolt is pinching the sidewall of brass against barrel extension, you have too much carrier speed. Heavier mass will help this. Additionally, reducing the gas pushed into the carrier will help. However, adding mass is the first route. Gas modulation can only do so much. I highly doubt your magazine springs are too weak. It is potential, but this usually applies to old and heavily used magazines. Your complaint would be it occurs only when some/one of the magazines are used.

If the headstamp is being pushed by bolt and the bullet is slammed into the barrel itself or the round chambers halfway, it most likely means the bullet is not ideal. You can reduce the COAL to attempt fixing this with handloads. I described a testing method for this earlier.

Alternatively, your buffer spring is too weak versus the magazine, ejector and extractor springs. This is also less likely. Meaning the forward momentum is too little to overcome the resistance. In this instance, the first thing to do would be increase the carrier and buffer mass, as heavy things are more difficult to stop moving. Momentum/inertia. Again, a stiffer spring and adding more gas can help this but.. more reciprocating weight is needed.

The creedmoor is almost certainly overgassed, so I do not believe undergassed is an issue. If you are using the recommended spring, I doubt that is an issue either.

 

[Quietguy88]

Also, be sure to keep the gas rings lubed, the ejector and extractor. It does not need to be dripping but a film of clean lubricant. In addition to the cam pin and bolt itself. Likewise, the buffer spring and buffer do best with a film of clean lubricant.

I am cheap, I use mobil1 full synthetic 0-20w. Because I buy a gallon for what a pint of clp costs. It is designed to purge carbon and soot, offers high lubricity, extreme load bearing and does not burn off all that fast. Find what works for you.

I am almost entirely convinced that using the a5 buffer tube(someone called this the armalite carbine setup. They are the same thing), a good spring, a full weight carrier and avoiding those super high bc bullets will fix your issue.

Simply, you did not mention strange wear or damage to the receivers, the bcg not going into battery on an empty chamber and only suffering feed issues intermittently.

All which the 6.5crapmore is known to suffer from. Because of light weight bcg and buffer, coupled with wrong ammo.

Share some photos of the issues. Check all the spots mentioned. Clean and lubricate the firearm. Perform the feeding test as described. Report back.

Most likely it is a very simple solution.

Best wishes. Keep us posted.

 

[357magag]

I have 1000rds 140 ELDM (stand one armory) and 800rds of Hornady 95gr varmint express.
So need to find combination of components to work with existing ammo.


Have V7 titanium buffer tube.

Also have a
JP LMOS with Titanium Fire Pin
GAP 10 BCG (from Hide Member)
KAK High Pressure Double Extractor BCG

 

[357magag]

I shoot 100% suppressed.
Removed can after being fed up with issues.

 

[XP1K]

Th

Is that last picture showing an extension that nests inside the bcg?

I have always wondered about the tubbs flatwire.

I used the 10oz rifle buffer from slash and the included spring. I changed, went to a5 tube and the kynshot. Forget which model number. It changed the feel. I had thought about trying the flatwire, but went with the sprinco red. Suppose one day I will spend the $20 on a flatwire.

That buffer is definitely huge. I bet the forward reset really pushes the muzzle down.

That little bit on the end does fit up inside carrier. Supposed to help with carrier tilt. I ended up taking some off of it as it was a pain to disassemble. Think it's about half of what's in that picture now.

I just shot a couple groups for function check. New scope for that gun should be here this week so I'm hoping to put some time on it this coming weekend.

 

[mtrmn]

I also have tried the KAK 6.5CM complete BCG it jammed.

So basically I need to ditch the JP SCS and JP LMOS bolt.
Full Mass Bolt (we wouldnt the KAK work?
Get a normal spring setup.

Yes. You're on the right track in your quest for reliability. I don't know anything about the JP spring setup, so I'll say go ahead and do away with that as well. The KISS principle is a good rule to follow. If you have an adjustable gas block, do all your troubleshooting with it wide open, at least until it runs better than it does now.
Sprinco.com and heavybuffers.com are good websites to help you with your decisions.
You'll need to know the internal depth of your buffer tube, either 7" or 7-3/4". This determines the length of your buffer. (2.5" or 3.25") AND the matched spring.
The length of your gas tube is pretty critical as well. It needs to terminate halfway of the cam pin cutout in the upper receiver. You can easily check this with the bcg locked rearward or removed and looking up through the magwell.
From what can see on the kak website that BCG should be full Mass and good to go.

 

[mtrmn]

I shoot 100% suppressed.
Removed can after being fed up with issues.

Yeah, need to initially get it running without the suppressor. That would increase the bolt speed even more. Once it runs ok without it, then you can put the suppressor back on and probably turn the gas down to compensate for the extra gas due to the suppressor.
Also, in your pics that's one long pointy bullet there. Actually appears to not be seated deep enough but I'm NOT familiar with 6.5 at all. Looks like it could cause some problems getting slambanged around in an AR though.
You have 2 perfectly fine BCGs from what I can see, just need to get a decent buffer and spring.

 

[bigjake83]

I have 1000rds 140 ELDM (stand one armory) and 800rds of Hornady 95gr varmint express.
So need to find combination of components to work with existing ammo.


Have V7 titanium buffer tube.

Also have a
JP LMOS with Titanium Fire Pin
GAP 10 BCG (from Hide Member)View attachment 7938625View attachment 7938626View attachment 7938627View attachment 7938628View attachment 7938629
KAK High Pressure Double Extractor BCG

Hold the fucking phone!!!

You're using the wrong SCS that's the AR15 model!!!

 

[Earnhardt]

Hold the fucking phone!!!

You're using the wrong SCS that's the AR15 model!!!

My LR-308 JP-SCS has 3 weights…is that it?

ETA…
I see it now too…great catch bigjake!
The AR15 model has a longer “bumper” at the base, and probably has a different overall length I’d guess.

 

[Earnhardt]

OK, next question…why does the OP’s JP-SCS only have 2 weights on it? (Even if it is an AR15 model)
All of the models on the JP website have 3 …(or more for the 9mm models)

 

[bigjake83]

OK, next question…why does the OP’s JP-SCS only have 2 weights on it? (Even if it is an AR15 model)
All of the models on the JP website have 3 or more…

The large frame SCS has 3 weights and a small base, the older small frame SCS has only 2 weights and a thicker bumper.. the overall lengths are the same that's why you can run a large frame SCS in a standard Carbine buffer tube.

That's a first Gen Small frame SCS

Whoever put this rig together is very special

 

[357magag]

So is my buffer tube to short?

And have several different ops on buffer?
I like the sound of 5oz hydraulic and red spring.
Vs adding another 5oz with heavy buffer.



Honestly, it needs a longer gas system. Using a full mass carrier, 5oz hydraulic buffer and a red spring. I am tempted to change from the red to orange spring, hoping to slow it down.

 

[CaptArab]

I would start with a slash heavy buffer and a toolcraft bcg.

Assuming nothing else is too wacky that should fix all your issues.

Just be warned though, that gun will be hard to tune with a high back pressure can.

Something like a sandman k, oss, or vented Helios would work well here IMO

 

[bigjake83]

So is my buffer tube to short?

And have several different ops on buffer?
I like the sound of 5oz hydraulic and red spring.
Vs adding another 5oz with heavy buffer.



Honestly, it needs a longer gas system. Using a full mass carrier, 5oz hydraulic buffer and a red spring. I am tempted to change from the red to orange spring, hoping to slow it down.

All you need is a Full mass carrier and a H2 buffer system that is correct for the Large frame system.

You have the carrier already, just order a H2 SCS and be done.

And for the love of God find someone who knows what they're doing to help you.

 

[XP1K]

The large frame SCS has 3 weights and a small base, the older small frame SCS has only 2 weights and a thicker bumper.. the overall lengths are the same that's why you can run a large frame SCS in a standard Carbine buffer tube.

That's a first Gen Small frame SCS

Whoever put this rig together is very special

I have both, the large and small frame scs but I don't use them. Not compatible with pws.

For some reason I want to say I remember my large frame version only having two weights because I remember thinking that was odd because the ar15 version I already had used three weights.

Maybe I've got it backwards. I don't know, they're probably mixed up in the wrong tubes now and I'll never know.

 

[2aBaC̶a̶]

Thats a wall of text. have you gone through the spring kit and tried at least one tungsten weight? I have a similar setup except an 18" WC barrel. it can be frustrating to find the right combination of buffer weight/spring/gas adjustment that doesnt beat up cases. ive settled on slightly dented and a pad on the deflector.

Im really surprised someone hasnt created a cause and effect chart for this yet.

(Question for everyone)
what is the real difference in changing weight to a buffer vs carrier when they work together as one?

 

[mtrmn]

It's all reciprocating mass so I don't think there is a difference as to which part you add weight to.

Spring rate, length and number of coils is just as important.

 

[mtrmn]

Sprinco USA -- Recoil Solutions

https://sprinco.com/SPRINCO-DOCS/Gas%20Mass%20and%20Springs%20AR%20Tuning.pdf

 

[Thorbeast]

Like others have said, slow down the cyclic rate. Almost all problems are from too fast a cyclic rate. Mag issues, extraction issues, ejection issues... they are all far more likely to be caused by too fast a cyclic rather than too slow a cyclic rate.

Before you start tinkering, please make sure you are using the correct length buffer tube and buffer weight for an AR10.

AR10s have longer BCGs... which means if you want to use a standard ar15 carbine buffer tube you will need a shorter buffer to accommodate the longer BCG in the buffer tube.

When changing stuff around... if you are going to use a standard ar15 carbine buffer tube, you will need a shorter buffer like this one (2.5" OAL):

Aero Precision AR-10 / 308 Carbine Buffer

M5 .308 Carbine Buffer for use in .308 Carbines with aA .308 Carbine Receiver Extension (buffer tube). This shorter .308 buffer is specific to .308 Carbines and will not work in .308 Rifles or AR15 platform firearms.This true mil-spec buffer is AMERICA Made and features three separate weights...

ar15discounts.com

The problem with the shorter buffers is, they have fewer weights in them, thus they can't be as heavy, so they won't be as effective as slowing down your cyclic rate.

If you are going to use a standard length ar15 carbine buffer, you will need an A5 length buffer tube. LMT, Armalite, Vltor, Magpul are the most common sources of these length buffer tubes. These buffer tubes are slightly longer and have enough length to accommodate both the longer ar10 BCG and ar15 carbine buffer.

My recommendation would be to start with an A5 length buffer tube (not sure what you currently have), full mass carrier, H3 buffer and a tubbs flatwire 308 spring.

This setup is cheap, but honestly, they should be, it's a spring and weight. Doesn't need to be complex or expense to work well. This is what I use on my LMT 308 (16" midlength gas). Adding the tubb 308 spring noticeably slowed down the cyclic rate and made the weapon much smoother and more enjoyable to shoot

There is a machine gun enthusiast who did a bunch of cyclic rate testing with different, buffer tubes, buffers and springs. Pretty much everything you can imagine (Tubb springs, springco springs, hydraulic buffers... everything). Very informative, worth your time, especially given what you are going through (link below).

Vltor A5 – My Personal Opinion and Testing,

Why the A5? Commonly known benefits of the A5 system: Allows usage of the rifle length spring Extends the LOP for those with long arms Longer buffers with...

c3junkie.com

Hope this helps.

 

[sinister]

Let's start with some known facts.

1. The Creedmoor has the potential for higher chamber and port pressure than 308/7.62.
2. This carbine will eventually be suppressed, so no matter what suppressor we're talking about the OP will eventually be boosting MORE gas, longer, back into the upper receiver.

There are a few things the OP can do, all of them requiring the system to smoothly operate through all stages of cycling, we're assuming both with and without a suppressor.

With a carbine or mid-length gas tube he's going to need to either control the amount of gas returning to the receiver, or add weight for the gas to work against, or both. Without going to a rifle-length or +1, +2, or +3 inches longer gas tube (to delay the gas column building enough pressure to start unlocking and extracting) he'll need an adjustable gas block to restrict what's getting bled out behind the bullet before it un-corks from either a plain muzzle or a suppressor. That's asking a lot.

Next would be a heavier buffer to make that gas do work. You don't want a stronger spring -- it may help delay unlocking a little, but it's also going to kick that bolt forward, faster than a longer cycling like you'll get with a Tubb flat-wire spring. You don't want the bolt carrier group going faster than the magazine spring can push the top cartridge into the magazine lips so the bolt can properly feed and chamber -- it's all in balancing timing so the operating cycle isn't interrupted.

KAC figured out suppressing the 16-inch SR-25 by using a rifle-length gas system.

 

[Ravenworks]

11.5oz? Dear lord.. did you grind a block of tungsten down???

Humor aside - how does that thing feel?

No but it makes the recoil cycle buttery smooth

 

[Quietguy88]

Like others have said, slow down the cyclic rate. Almost all problems are from too fast a cyclic rate. Mag issues, extraction issues, ejection issues... they are all far more likely to be caused by too fast a cyclic rather than too slow a cyclic rate.

Before you start tinkering, please make sure you are using the correct length buffer tube and buffer weight for an AR10.

AR10s have longer BCGs... which means if you want to use a standard ar15 carbine buffer tube you will need a shorter buffer to accommodate the longer BCG in the buffer tube.

When changing stuff around... if you are going to use a standard ar15 carbine buffer tube, you will need a shorter buffer like this one (2.5" OAL):

Aero Precision AR-10 / 308 Carbine Buffer

M5 .308 Carbine Buffer for use in .308 Carbines with aA .308 Carbine Receiver Extension (buffer tube). This shorter .308 buffer is specific to .308 Carbines and will not work in .308 Rifles or AR15 platform firearms.This true mil-spec buffer is AMERICA Made and features three separate weights...

ar15discounts.com

The problem with the shorter buffers is, they have fewer weights in them, thus they can't be as heavy, so they won't be as effective as slowing down your cyclic rate.

If you are going to use a standard length ar15 carbine buffer, you will need an A5 length buffer tube. LMT, Armalite, Vltor, Magpul are the most common sources of these length buffer tubes. These buffer tubes are slightly longer and have enough length to accommodate both the longer ar10 BCG and ar15 carbine buffer.

My recommendation would be to start with an A5 length buffer tube (not sure what you currently have), full mass carrier, H3 buffer and a tubbs flatwire 308 spring.

This setup is cheap, but honestly, they should be, it's a spring and weight. Doesn't need to be complex or expense to work well. This is what I use on my LMT 308 (16" midlength gas). Adding the tubb 308 spring noticeably slowed down the cyclic rate and made the weapon much smoother and more enjoyable to shoot

There is a machine gun enthusiast who did a bunch of cyclic rate testing with different, buffer tubes, buffers and springs. Pretty much everything you can imagine (Tubb springs, springco springs, hydraulic buffers... everything). Very informative, worth your time, especially given what you are going through (link below).

Vltor A5 – My Personal Opinion and Testing,

Why the A5? Commonly known benefits of the A5 system: Allows usage of the rifle length spring Extends the LOP for those with long arms Longer buffers with...

c3junkie.com

Hope this helps.

Best post so far.

Honestly, the OP should be using the 125 to 135gr vmax or whatever in 308 if they want a 16" suppressed hog buster. 16" 1:10 twist with a rifle gas. Use a 5oz buffer as minimum weight

 

[Quietguy88]

Let's start with some known facts.

1. The Creedmoor has the potential for higher chamber and port pressure than 308/7.62.
2. This carbine will eventually be suppressed, so no matter what suppressor we're talking about the OP will eventually be boosting MORE gas, longer, back into the upper receiver.

There are a few things the OP can do, all of them requiring the system to smoothly operate through all stages of cycling, we're assuming both with and without a suppressor.

With a carbine or mid-length gas tube he's going to need to either control the amount of gas returning to the receiver, or add weight for the gas to work against, or both. Without going to a rifle-length or +1, +2, or +3 inches longer gas tube (to delay the gas column building enough pressure to start unlocking and extracting) he'll need an adjustable gas block to restrict what's getting bled out behind the bullet before it un-corks from either a plain muzzle or a suppressor. That's asking a lot.

Next would be a heavier buffer to make that gas do work. You don't want a stronger spring -- it may help delay unlocking a little, but it's also going to kick that bolt forward, faster than a longer cycling like you'll get with a Tubb flat-wire spring. You don't want the bolt carrier group going faster than the magazine spring can push the top cartridge into the magazine lips so the bolt can properly feed and chamber -- it's all in balancing timing so the operating cycle isn't interrupted.

KAC figured out suppressing the 16-inch SR-25 by using a rifle-length gas system.

I have limited experience with flat wires.

Care to explain more about the longer cycling comment? To me, the travel distance is the same as is the compression. Now, it may be less of a 'actual compression vs max compression' different percent than a typical round wire. Like the tubbs may be a 50% compressed spring at full rearward travel, whereas the round wire may be 85%..

I do not understand, please educate me.

Thank you.

 

[CaptArab]

A lot of folks are going to disagree with me here, but IME large frames just don't run well suppressed with typical medium to high back pressure cans.

You have to adjust the gas block to such a narrow window that a tiny click or partial turn goes from not cycling to 1-2 o clock harsh ejection and malfunctions.

20 rounds later the gun is so dirty and dry it needs another coat of oil or more gas.

The only system that isn't a pita IMO is a super low back pressure (oss or similar) can with a rlgs. I prefer a 16" barrel.

I'm sure others will chime in and say their mid length 18" works great with their sico omega or whatever but speaking from personal experience those setups have run like crap for me.

 

[357magag]

This the is buffer tube I have.​

V SEVEN 2055 Carbine Buffer Tube A5​

8"

--I am using a Sico Omega


So the setup below should fix my issue?


Hydraulic KynSHOT Recoil Buffer AR-10 Carbine (3.25") (soft shooting than standard resulting in quicker follow up shots on hawgs)

&​

JP .308 carbine buffer spring (suppose to run quiter)