Ideal buffer weight for an AR-10 6.5 Creedmoor with an adjustable gas block and A5 buffer tube?

[DontWorryScro]

I'm slowly piecing together a 6.5 Creedmoor from a matching Aero M5 receiver set I bought on sale last year. I had help with a build list from a buddy who knows way more about specs than I do so this build will include a JP .308 AR Enhanced HP bolt completion group and a JP 308 Low Mass bolt carrier. Also an adjustable gas block will be on the list once I determine what barrel profile I will go with. But the one area I've seen confusing info on is buffer weight selection when using an AGB in concert with an A5 receiver extension. My buddy says the AGB mostly negates the need for a heavy H3 3.25" carbine buffer but VLTOR suggested that I keep the heavy weight in order to ensure proper cycling. My friend also recommended a Tubb flat wire where VLTOR did not like the flat wound springs and suggested a stock Armalight rifle length 308 spring or something by SpringCo.

Do we have any people with experience with this kind of set up who could offer some advice? Thank you.

 

[LawnMM]

Run a regular weight carrier, you can do a JP SCS instead of a flatwire but make sure it has the tungsten weights, put a superlative arms AGB on it.

Light weight components don't mix well with AR10s you wind up with the bolt unlocking early and over gassing issues.

JP makes it work by using extended length gas systems and likely custom gas port diameters on their in house barrels. It's not all mix and match and no problems like with AR15s.

 

[DontWorryScro]

Since it is with an A5 receiver extension you would prefer to hacksaw the 308 JP SCS spacer to make it fit?

I do plan on going with a +2 gas system which may alleviate some of the issues you mentioned.

 

[LawnMM]

I haven't messed with any of the A5 stuff, did you already buy it? If so heavy buffer and stiff spring... whatever that system entails to achieve those goals.

Superlative Arms makes the best AGB I've tried yet and was the ONLY one to help tame my AR10's gas system.

 

[mudpig]

I've recently tried the Tubb flat wire springs and really like them in 4 of my big AR's. And with an AGB really makes them tunable and sweet cycling.

 

[ballistic1]

I run SLR Sentry 7's on my 6 Creed and 6.5 Creed Small framed Ar10. Both Bartlein 16", both +2 gas.
Vltor RE-A5 buffer tube with standard weight buffer and spring
Always suppressed with my Rugged Surge.

They were purpose built to be night coyote guns, hence the 16" bbls.
Craddock spun up both bbls


Both run like Singer Sewing machines. Smooth, flawless.

I was told what I was building wdn't run or work by a few people. I did it anyway
and they work perfectly excellent

 

[Pusher591]

Just curious but Craddock is spinning me a 20” 6.5 Creed barrel with a +1 gas system. I’m running a full weight SLR BCG with the bolt matched to barrel. I currently have the JP SCS for standard 308, but wondering if I need the H2 version?

I will also be running a badger thruster Brake and have no plans to run it suppressed. Will I be ok or will recoil still be pretty sharp with the standard JP SCS? Sorry to hi-jack but question is in line with the original intent of the thread so hopefully answers will help everyone.

 

[padom]

Nothing wrong with JP LMOS carrier. I've built 15+ 6.5cm gassers to date with Rubber City full mass and JP LMOS. Both run 100% reliably. With the LMOS you should be running a JP SCS Heavy with 1 Tungsten weight and 2 steel and the 2nd from heaviest spring in their spring pack. Smooth as butter and brass looks like its fired out of a bolt gun. SA is tuned to lock back on last round.

With a full mass bcg no heavy buffer needed. I find the LMOS/SCS Heavy combinatuon provides the lightest felt recoil. The full mass buffer has a recoil impulse that is much heavier/hard hitting in the shoulder.

 

[DontWorryScro]

Nothing wrong with JP LMOS carrier. I've built 15+ 6.5cm gassers to date with Rubber City full mass and JP LMOS. Both run 100% reliably. With the LMOS you should be running a JP SCS Heavy with 1 Tungsten weight and 2 steel and the 2nd from heaviest spring in their spring pack. Smooth as butter and brass looks like its fired out of a bolt gun. SA is tuned to lock back on last round.

With a full mass bcg no heavy buffer needed. I find the LMOS/SCS Heavy combinatuon provides the lightest felt recoil. The full mass buffer has a recoil impulse that is much heavier/hard hitting in the shoulder.

I plan on using an A5 receiver extension which means cutting the spacer down some with a hacksaw if I go the JP SCS route. But this seems to not be a deterrent to most people. People like the SCS more than the Tubb flat wire or Springco oranges? Totally valid, of course, I'm just trying to consolidate overall sentiment. JP Silent Captured Spring seems to have a loyal fan base.

 

[Pusher591]

Nothing wrong with JP LMOS carrier. I've built 15+ 6.5cm gassers to date with Rubber City full mass and JP LMOS. Both run 100% reliably. With the LMOS you should be running a JP SCS Heavy with 1 Tungsten weight and 2 steel and the 2nd from heaviest spring in their spring pack. Smooth as butter and brass looks like its fired out of a bolt gun. SA is tuned to lock back on last round.

With a full mass bcg no heavy buffer needed. I find the LMOS/SCS Heavy combinatuon provides the lightest felt recoil. The full mass buffer has a recoil impulse that is much heavier/hard hitting in the shoulder.

I do not have an adjustable gas block, only the standard SLR lo-pro and would prefer to stick with it. It seems I probably need to order at least one tungsten weight for the SCS. I’ll try it first with the standard all steel weights first and see how it feels.

 

[padom]

I plan on using an A5 receiver extension which means cutting the spacer down some with a hacksaw if I go the JP SCS route. But this seems to not be a deterrent to most people. People like the SCS more than the Tubb flat wire or Springco oranges? Totally valid, of course, I'm just trying to consolidate overall sentiment. JP Silent Captured Spring seems to have a loyal fan base.

I like them because they are fully tunable. Get the SCS Heavy with the spring pack. Go to the range and try different weight/spring combos till you have no case head damage which is usually caused by the carrier unlocking too early.

Like I said, 1 tungsten and 2 steel with second heaviest spring is what works with LMOS in multiple builds for me.

I do not have an adjustable gas block, only the standard SLR lo-pro and would prefer to stick with it. It seems I probably need to order at least one tungsten weight for the SCS. I’ll try it first with the standard all steel weights first and see how it feels.

Looks like you said you have a SLR full weight carrier so you wont need any tungsten weights. I would start with the spring pack and play with the springs.

 

[awpk03s]

There’s nothing wrong with cutting down the JP spacer when using the AR10 SCS.
I could be wrong but I think the instructions even talk about doing just that, if you need the spacer, put it in, if it’s too long then well cut it down.
I’ve got two 6.5s and one 308 using SCS Heavys and have a cut down spacer in the buffer tube.

 

[chickon1]

I've built an 6.5 and a .308 and not sure where all the "over-gassed" issue is coming from. My 6.5 would not lock the bolt back at all with the gas port wide open. My .308 runs prefect with the gas block fully opened. I can get away with closing the gas port a bit with he lower grans.

I'm running the JP LM and it cycles great.. What you have to be careful with is there is 2 different length rifle buffers. I bought some "custom" buffer labeled for .308 and could never get my 6.5 or .308 to cycle with it.. It's probably about an inch longer.

My opinion, buy the cheapest factory crap first, because it will probably work, then start tuning from there. You will drive yourself insane and spend a buttload of money trying to do all the crazy setup first.

Polished springs are a little bit quieter.

 

[JHARPE40]

Nothing wrong with JP LMOS carrier. I've built 15+ 6.5cm gassers to date with Rubber City full mass and JP LMOS. Both run 100% reliably. With the LMOS you should be running a JP SCS Heavy with 1 Tungsten weight and 2 steel and the 2nd from heaviest spring in their spring pack. Smooth as butter and brass looks like its fired out of a bolt gun. SA is tuned to lock back on last round.

With a full mass bcg no heavy buffer needed. I find the LMOS/SCS Heavy combinatuon provides the lightest felt recoil. The full mass buffer has a recoil impulse that is much heavier/hard hitting in the shoulder.

Do I have to order the Tungsten weights separately or does it come in the JPSCS builder kit ?

 

[padom]

Do I have to order the Tungsten weights separately or does it come in the JPSCS builder kit ?

Not if you order the "HEAVY" version...then just buy the SCS Alternate Spring Pack AR10 seperate....

JP Rifles

JP Rifles

 

[JHARPE40]

Not if you order the "HEAVY" version...then just buy the SCS Alternate Spring Pack AR10 seperate....

JP Rifles

JP Rifles

This the model I am ordering

 

[padom]

This the model I am ordering
View attachment 7343419

Not sure its the same...i can see it doesnt come with the spring that tuned the 10+ I built "yellow/red"

Not sure if weight is identical or not

 

[_Windrider_]

Honestly all you need is the 10H2 SCS. But if you buy the builder kit it comes with everything you need SCS +3 springs of different weight and a spacer if using an A2 extension. I run an H2 witha Full Mass BCG and H2 Bolt. no issues ever.

One thing that is not included and is not required, is a retainer pin for the SCS system, but if you want one the part number is JPSCS-BRP

 

[chickon1]

Don't waste your money on the JP spring set. Does the same thing as a regular spring and buffer, but cost way more to tune it.

I would buy an normal spring set for the rifle tube.. you want the buffer is light as you can get it to reduce the recoil force that can throw off your shot. Same concept with the JP LMOS, which is awesome and worth the money. ( None of this is a big deal unless you are shooting over 500 yds or so.)

I have tried to build this to run in the Gas PRS division, which sucks sometimes because some places just call it the "tactical" division, which has bolt guns in it.

My DPMS 6.5CM holds little over 1-1/2 inch groups @300 yards with factory 140 ELD.

I also highly recommend the JP handguards..

 

[padom]

Don't waste your money on the JP spring set. Does the same thing as a regular spring and buffer, but cost way more to tune it.

I would buy an normal spring set for the rifle tube.. you want the buffer is light as you can get it to reduce the recoil force that can throw off your shot. Same concept with the JP LMOS, which is awesome and worth the money. ( None of this is a big deal unless you are shooting over 500 yds or so.)

I have tried to build this to run in the Gas PRS division, which sucks sometimes because some places just call it the "tactical" division, which has bolt guns in it.

My DPMS 6.5CM holds little over 1-1/2 inch groups @300 yards with factory 140 ELD.

I also highly recommend the JP handguards..

You have zero idea what you're talking about. Buffer weight tuning has nothing to do with reducing recoil that "throws off your shot"....


The whole point of proper buffer/spring tuning is lock time. It's tuned in conjuction with your gas block to ensure the BCG isn't moving before pressure subsides...you are trying to keep your bcg locked till pressure drops so your not ripping your case out of the chamber...this is where all your brass damage comes from when you're not properly tuned

Guys think oh I built a 6.5cm and it works but have no idea what properly tuning it means and why....


Whats your sample size? I've built what 30+ 6.5cm gasers from rifle gas, to +2 gas, heavy buffers, every spring combo you can buy, slash buffers, to JP SCS.....My 6.5cm gasser accuracy and brass that looks like it was fired from a Bolt gun speak for themselves..


Stay tuned....youll see my current Bartlein 6.5cm gasser head to head with Bartleins new 6.5cm carbon barrel shortly in my upcoming review

 

[chooter]

Try a Colt hydraulic buffer.

 

[chickon1]

You have zero idea what you're talking about. Buffer weight tuning has nothing to do with reducing recoil that "throws off your shot"....


The whole point of proper buffer/spring tuning is lock time. It's tuned in conjuction with your gas block to ensure the BCG isn't moving before pressure subsides...you are trying to keep your bcg locked till pressure drops so your not ripping your case out of the chamber...this is where all your brass damage comes from when you're not properly tuned

Guys think oh I built a 6.5cm and it works but have no idea what properly tuning it means and why....


Whats your sample size? I've built what 30+ 6.5cm gasers from rifle gas, to +2 gas, heavy buffers, every spring combo you can buy, slash buffers, to JP SCS.....My 6.5cm gasser accuracy and brass that looks like it was fired from a Bolt gun speak for themselves..


Stay tuned....youll see my current Bartlein 6.5cm gasser head to head with Bartleins new 6.5cm carbon barrel shortly in my upcoming review

Being a Engineer by trade, I setup a jig with a piece of pipe where the spring fit in perfectly, added weights an looked at how much the spring would compress with certain amount of weight. I also checked how much weight the spring would hold before it started compressing. There are different types of springs with different compression rates as well.( Flat wire vs Round wire) So I had to take that into account for bolt pressure when closed. There are shitty springs and good springs made up of different medal compositions which affect the performance and life of the spring.. just like on your lift 4x4

My thoughts for precision shooting:
-Figuring out the ft lbs required to keep the bolt in place long as possible without screwing up the round ejection is the sweet spot I think.
-Ensure the bolt doesn't compress the spring completely causing the bolt "bounce"
-Ensure the least amount of recoil for shot follow ups and spotting impacts.
-Last but not least, tuning the gas for a specific round for the least amount pressure to get the bolt to lock back and run through a 10 round mag with no issues.

Start with one variable, tune that variable (spring) to the sweet spot, move to the next variable, the buffer, tune to the sweet spot.

I like this guys flat wire springs . ( This dude has a a lot better tools than I did)

Tubb Precision AR-15 Flatwire Buffer Spring (Fits both Carbine and Standard length stocks)

Tubb Precision AR-15 CS Buffer Spring; High Performance Tubb Precision Flatwire Buffer Spring.

www.davidtubb.com