6.5 creedmoor AR Only

[PovertyStateArmorer]

I am definitely seeing a lot of loads on what seems like the bleeding edge. I am pretty new to reloading and have been getting some great accuracy with my best group below. I am utilizing an A&D 120i and an OpenTrickler to weigh my charges. My problem is that with moderate loads, I am still seeing pressure signs like bright ejector marks on the brass. I know the brass is not the best.

22" 6.5cm Criterion barrel

ELD- Match 130 gr
StaBall6.5 43.1 gr
Sellier Bellot Brass
CCI BR2 primers

Average velocity: ~2860fps
SD: ~13
ES: ~50

I have just ordered some Lapua LRP brass and want to try some 140 or 147 grain projectiles. Would appreciate some feedback on setting this rifle up for 1000 yards safely.

 

[ZA206]

Did the first round of the "Final" seating depth confirmations on my 140 Berger Hybrid load for my 24" Proof barreled AR10. I'd say 2.117" CBTO is off to a good start... LOL. This was shot at 100 yards, out of the bed of my truck using a game changer bag up front and a squeeze bag in the rear.

2785 fps
SD =1.6


-ZA

 

[Basic user]

I seen several people here talking about early extraction and super heavy buffer and really tough springs. My questions are, is doing this necessary because you dont have an adjustable gas block? Is reducing the gas down to where it barely functions the same as using a really heavy buffer? And, if it's not, and you run a really heavy buffer/tough spring, wont you now have to really increase the gas to get that to cycle?

 

[JR1200W3]

I seen several people here talking about early extraction and super heavy buffer and really tough springs. My questions are, is doing this necessary because you dont have an adjustable gas block? Is reducing the gas down to where it barely functions the same as using a really heavy buffer? And, if it's not, and you run a really heavy buffer/tough spring, wont you now have to really increase the gas to get that to cycle?

The buffer weight , BCG weight, and gas port size are interdependent on one another. So, yes....if you don't tune your gas, you can try to compensate by increasing buffer weight and spring strength but that's a poor way to do it because you'll have more resiprocating weight and you'll feel it in recoil and recovery. You're best off starting from front to back sizing your gas port to the buffer you want to run. BCG weight can be a factor as well, not just buffers. A good example of your question is JP's loMass BCG and tunable gas block and SCS. You can configure all three to reduce the reciprocating mass as light as possible which greatly reduces part of recoil and can speed up cycling. Now, it is possible to go too far with that and compromise reliability. You need a certain amount of recoiling mass coming forward to overcome carbon sludge when the gun gets dirty. So there's a limit to tuning. In my experience with AGBs, JP LoMass BCGs, and SCS's in large frame guns, I couldn't just tune to lock back. I ended up having to add a little bit of extra buffer weight to eliminate ejector and extractor tears in the case head. So there's also something to the idea of fine tuning buffer weight to reduce early unlocking. But IMO, it should be fine tuning. Not using the buffer to tune the lock back or function of the gun. I think you set a reasonable buffer weight that allows for a little future tuning up or down, adjusting gas for lockback, then going back to buffer weight if need be to eliminate early unlocking. This is why I like SCSs. The steel and tungsten buffer weights are pretty convenient for tuning.

If you're buying a stock barrel, yes...get an AGB. Ideally you have a barrel made by a Smith that drills the gas port to function in your gun as you have it configured. (Dwell + BCG + buffer/ spring + established load).

 

[Earnhardt]

The buffer weight , BCG weight, and gas port size are interdependent on one another. So, yes....if you don't tune your gas, you can try to compensate by increasing buffer weight and spring strength but that's a poor way to do it because you'll have more resiprocating weight and you'll feel it in recoil and recovery. You're best off starting from front to back sizing your gas port to the buffer you want to run. BCG weight can be a factor as well, not just buffers. A good example of your question is JP's loMass BCG and tunable gas block and SCS. You can configure all three to reduce the reciprocating mass as light as possible which greatly reduces part of recoil and can speed up cycling. Now, it is possible to go too far with that and compromise reliability. You need a certain amount of recoiling mass coming forward to overcome carbon sludge when the gun gets dirty. So there's a limit to tuning. In my experience with AGBs, JP LoMass BCGs, and SCS's in large frame guns, I couldn't just tune to lock back. I ended up having to add a little bit of extra buffer weight to eliminate ejector and extractor tears in the case head. So there's also something to the idea of fine tuning buffer weight to reduce early unlocking. But IMO, it should be fine tuning. Not using the buffer to tune the lock back or function of the gun. I think you set a reasonable buffer weight that allows for a little future tuning up or down, adjusting gas for lockback, then going back to buffer weight if need be to eliminate early unlocking. This is why I like SCSs. The steel and tungsten buffer weights are pretty convenient for tuning.

If you're buying a stock barrel, yes...get an AGB. Ideally you have a barrel made by a Smith that drills the gas port to function in your gun as you have it configured. (Dwell + BCG + buffer/ spring + established load).

Great post man!

It doesn’t get much better than this when it comes to describing how to tune an LR 308, or long action AR!

 

[Top O' Texas]

I seen several people here talking about early extraction and super heavy buffer and really tough springs. My questions are, is doing this necessary because you dont have an adjustable gas block? Is reducing the gas down to where it barely functions the same as using a really heavy buffer? And, if it's not, and you run a really heavy buffer/tough spring, wont you now have to really increase the gas to get that to cycle?

The only time the need of a heavier buffer or extra weight anything is because of an incorrect gas port size as location isn't as important! I can state that as 100% fact/correct due to shooting an 18" w/intermediate gas and 22" w/rifle length gas systems from Aero precision in 6.5creed w/o the use of an agb. Cycles great and doesn't ruin/harm brass. 5 other brands of barrels from rifle to +2 i can't will operate as good w/o any agb and/or a heavier buffer! Ammo used was Hornady 123sst and 123a-max match.

 

[Shotafterdark]

42.2 gr Imr 4064
100 gr Hornady Eld VT

Out of my 22" AR10
3250 fps ..

Same load out of my Tikka custom with a 26" Excalibur barrel is 3280 fps
Im a yote hunter .

Both group at 1/2 moa easy .

 

[Shotafterdark]

My AR10 has a superlative arms gas block to minimize gas to my RCA bcg as it's titanium and extremely sensitive to gas .

H4 buffer .
With a 10 ring Raptor and 6" reflex .
It keeps the pressure up enough to match velocity in a 22" to my 26" bolt gun.

 

[JR1200W3]

My AR10 has a superlative arms gas block to minimize gas to my RCA bcg as it's titanium and extremely sensitive to gas .

H4 buffer .
With a 10 ring Raptor and 6" reflex .
It keeps the pressure up enough to match velocity in a 22" to my 26" bolt gun.

This is a good example. I had a conversation about this with another shooter who was trying to tune a 22-in barrel 6 Arc AR-15 using JP parts. He was describing how he started off with a low mass BCG but had to keep adding buffer weight in addition to adjusting his gas and he felt like he was going around and around about it. He commented about how potentially self-defeating using a low-mass BCG with heavy buffers was. I don't truly know if BCG weight is significantly different or independent than buffer weight when it comes to the entire system, but it seems like going 20/80 or 50/50 on a BCG and buffer in combined operation seems like it would just be the same thing.

 

[Shotafterdark]

This is a good example. I had a conversation about this with another shooter who was trying to tune a 22-in barrel 6 Arc AR-15 using JP parts. He was describing how he started off with a low mass BCG but had to keep adding buffer weight in addition to adjusting his gas and he felt like he was going around and around about it. He commented about how potentially self-defeating using a low-mass BCG with heavy buffers was. I don't truly know if BCG weight is significantly different or independent than buffer weight when it comes to the entire system, but it seems like going 20/80 or 50/50 on a BCG and buffer in combined operation seems like it would just be the same thing.

I actually bought the bolt carrier for the sole reason of attempting to steal as little energy from the round as I have 22 cycle the action.And try to approach both action velocity in a shorter barrel gas gun

I feel I nailed it because I am right there with my bolt gun and velocity

But I had to work it up slowly and be careful, because it will literally beat the shit out of your gun.If you're not careful that won't carrier.Being that light is really something else


It was a lot like working up a load

 

[Shotafterdark]

The concept actually works very well
Start out with a very light bolt carrier
And obviously the most important part is the ability to adjust the gas

Stealing just enough to cycle the action and no more

I was shocked at how sensitive it is
I found the sweet spot with a heavier buffer

There is something about having the bolt carrier group as the load up front

That makes the difference when it is lighter
And then slowing down its momentum with a heavier buffer

Even with the adjustment on the gas block that heavier buffer was still needed


So in the end, you have to ask yourself as the mass is still heavier with a h four buffer

Did it make a difference?And yes it did

I was able to achieve the velocities, I set out to

 

[Basic user]

The buffer weight , BCG weight, and gas port size are interdependent on one another. So, yes....if you don't tune your gas, you can try to compensate by increasing buffer weight and spring strength but that's a poor way to do it because you'll have more resiprocating weight and you'll feel it in recoil and recovery. You're best off starting from front to back sizing your gas port to the buffer you want to run. BCG weight can be a factor as well, not just buffers. A good example of your question is JP's loMass BCG and tunable gas block and SCS. You can configure all three to reduce the reciprocating mass as light as possible which greatly reduces part of recoil and can speed up cycling. Now, it is possible to go too far with that and compromise reliability. You need a certain amount of recoiling mass coming forward to overcome carbon sludge when the gun gets dirty. So there's a limit to tuning. In my experience with AGBs, JP LoMass BCGs, and SCS's in large frame guns, I couldn't just tune to lock back. I ended up having to add a little bit of extra buffer weight to eliminate ejector and extractor tears in the case head. So there's also something to the idea of fine tuning buffer weight to reduce early unlocking. But IMO, it should be fine tuning. Not using the buffer to tune the lock back or function of the gun. I think you set a reasonable buffer weight that allows for a little future tuning up or down, adjusting gas for lockback, then going back to buffer weight if need be to eliminate early unlocking. This is why I like SCSs. The steel and tungsten buffer weights are pretty convenient for tuning.

If you're buying a stock barrel, yes...get an AGB. Ideally you have a barrel made by a Smith that drills the gas port to function in your gun as you have it configured. (Dwell + BCG + buffer/ spring + established load).

(I should preface this with I'm working with a 20" barrel) Can you expand on those two sentences in red? By 'extra' buffer weight, extra to what? You mean heavier than the standard issue H2's and the like? And heavier buffers reduce/stop ejector and extractor tears? Can you tell me a tad more on these tears? And lastly, buffer weight to reduce early unlocking; are you meaning that it's early unlocking that's causing ejector & extractor tears? Or is early unlocking a whole separate issue you're trying to address. I appreciate your help thus far.

 

[padom]

(I should preface this with I'm working with a 20" barrel) Can you expand on those two sentences in red? By 'extra' buffer weight, extra to what? You mean heavier than the standard issue H2's and the like? And heavier buffers reduce/stop ejector and extractor tears? Can you tell me a tad more on these tears? And lastly, buffer weight to reduce early unlocking; are you meaning that it's early unlocking that's causing ejector & extractor tears? Or is early unlocking a whole separate issue you're trying to address. I appreciate your help thus far.

Ive explained this in detail numerous times.

But the purpose of tuning your large frame gasser is to make sure your BCG doesn't start moving before your case has shrunk bsck down so your aren't ripping it out of the chamber while its expanded against the chamber walls.

Most improperly tuned large frame gassers shoot but are rough and brass is torn up. Swiped and burs on case head because bcg is ripping the case out of the chsmber before pressure has subsided and brass has shrunk back down...

Proper tuning is to ensure you lock back on empty mag and bcg isnt moving until case has shrunk bsck down...

 

[Shotafterdark]

Ive explained this in detail numerous times.

But the purpose of tuning your large frame gasser is to make sure your BCG doesn't start moving before your case has shrunk bsck down so your aren't ripping it out of the chamber while its expanded against the chamber walls.

Most improperly tuned large frame gassers shoot but are rough and brass is torn up. Swiped and burs on case head because bcg is ripping the case out of the chsmber before pressure has subsided and brass has shrunk back down...

Proper tuning is to ensure you lock back on empty mag and bcg isnt moving until case has shrunk bsck down...

I guess I better keep my chamber polished like glass

 

[Shotafterdark]

You know i'm having a hard time understanding this worry of yours

The expansion is going to take place fully before the cam.Lugs on the bolt rotate to disengage

I'm able to simply perform this action with less gas expenditure and less pressure.Taken away from the bore, thus, i'm not losing velocity

 

[JR1200W3]

You know i'm having a hard time understanding this worry of yours

The expansion is going to take place fully before the cam.Lugs on the bolt rotate to disengage

I'm able to simply perform this action with less gas expenditure and less pressure.Taken away from the bore, thus, i'm not losing velocity

Padom isn't arguing with you. He's responding to Basic User. He's not making any comments about your titanium BCG. You don't have to defend yourself. But that said, The unlocking action can happen before the case has constricted and as the bolt tries to pull the brass out of the chamber, it still has too much friction and that's what causes the burrs and tearing of the case rim. This is early unlocking. If you are trying to argue that this is not a thing with some rifles, you are just going to look foolish. It's a pretty well known fact. Add a little additional buffer weight behind it to slow down the unlocking to allow the case to fully contract and release friction from the chamber wall.

 

[JR1200W3]

(I should preface this with I'm working with a 20" barrel) Can you expand on those two sentences in red? By 'extra' buffer weight, extra to what? You mean heavier than the standard issue H2's and the like? Yes

Yes

And heavier buffers reduce/stop ejector and extractor tears? Can you tell me a tad more on these tears?

I don't think it would be accurate to just generalize and say the heavier buffers stop early unlocking. You need to have the gun tuned and then if you still have early unlocking then you add a little bit more buffer weight in the hopes that it slows down the early unlocking. So no and yes answer to that.

And lastly, buffer weight to reduce early unlocking; are you meaning that it's early unlocking that's causing ejector & extractor tears?

Yes

Or is early unlocking a whole separate issue you're trying to address.

No

I don't know if there is a standard buffer weight but I was generally just referring to an H2 or H3. However
I am using the JP SCS system. It is a captured spring and it holds three buffer weights that looks like large silver rings. They come in steel or tungsten. You can configure the three of them in a mix in between the two or even have all tungsten buffers. This is how you adjust the weight of the buffer in this system. So for instance I might have two steel buffers and one tungsten buffer and the gun locks back. But I'm still getting just a bit of ejector swipe on the case head so I replace a steel with a tungsten weight And now I am running two tungsten's and one steel for a heavier buffer. This eliminates any tearing or smearing of the case head. It is the same concept for buffers but I just don't use standard buffers in large frame gas guns.

Plus everything Padom said.

 

[JR1200W3]

I actually bought the bolt carrier for the sole reason of attempting to steal as little energy from the round as I have 22 cycle the action.And try to approach both action velocity in a shorter barrel gas gun

I feel I nailed it because I am right there with my bolt gun and velocity

But I had to work it up slowly and be careful, because it will literally beat the shit out of your gun.If you're not careful that won't carrier.Being that light is really something else


It was a lot like working up a load

To be honest, I don't think I'm too far off what you're doing. I am using JP low mass bolt carriers and my SCS systems in both large frame guns are using two tungsten buffers and one steel buffer. The brass looks like it came out of a bolt gun. This is probably something like an H3. Unfortunately I have not been able to configure it as an H1 and turn the gas down until it locks back and still not have early unlocking so I have had to go up in buffer weight as a result. It does work but it just seems a little self-defeating and pointless if I could just run a standard weight carrier and an H2. You have to ask yourself, are you really getting the benefits of a low mass carrier if the reciprocating weight is the same. As far as some sort of special sauce or magic to having the weight forward or back, I think that would be pretty hard to prove.

 

[Top O' Texas]

Gas to the key is where any unlocking will begin regardless of bcg and buffer wright! Heavier buffers only slow down bcg velocity! Sure there's a fine line where it might make some difference? Shut the gas off and if it unlocks there's a leakage. Can't say this enough, gas port size trumps all for every problem. Properly sized gas port (using a non-agb & ~3oz buffer) it WILL NOT have any or cause any brass damage. I have 2 6.5creed AR's I shoot this way.

 

[Basic user]

Yes

I don't think it would be accurate to just generalize and say the heavier buffers stop early unlocking. You need to have the gun tuned and then if you still have early unlocking then you add a little bit more buffer weight in the hopes that it slows down the early unlocking. So no and yes answer to that.

Yes

No

I don't know if there is a standard buffer weight but I was generally just referring to an H2 or H3. However
I am using the JP SCS system. It is a captured spring and it holds three buffer weights that looks like large silver rings. They come in steel or tungsten. You can configure the three of them in a mix in between the two or even have all tungsten buffers. This is how you adjust the weight of the buffer in this system. So for instance I might have two steel buffers and one tungsten buffer and the gun locks back. But I'm still getting just a bit of ejector swipe on the case head so I replace a steel with a tungsten weight And now I am running two tungsten's and one steel for a heavier buffer. This eliminates any tearing or smearing of the case head. It is the same concept for buffers but I just don't use standard buffers in large frame gas guns.

Plus everything Padom said.

I do understand the premature extraction concept; I just wasn't sure if that was what is causing the swipes and burrs; I just needed that confirmation. I think I'm at a 5oz buffer now, I cant remember but I will check when I get home. I'm just wondering what the weight threshold was, for when your gas blocks all the way down to where the carrier just locks up when empty, and you're running a 5oz buffer and you're still getting the swipes and burrs. Do we still keep going up in buffer weight? I kind of felt like that 5 was the max. I was also a little confused on if you're gas is already as low as it can get, and your buffers pretty heavy, and then you add even more buffer, now the gas is going to have to get raised back up a little to move that extra mass; wont that put you right back where you were when the gas was 2 clicks tighter and .2-.3oz lighter in the buffer?

 

[Shotafterdark]

Not to mention my brass coming out of this gun doesn't look any different than any my others

Padom isn't arguing with you. He's responding to Basic User. He's not making any comments about your titanium BCG. You don't have to defend yourself. But that said, The unlocking action can happen before the case has constricted and as the bolt tries to pull the brass out of the chamber, it still has too much friction and that's what causes the burrs and tearing of the case rim. This is early unlocking. If you are trying to argue that this is not a thing with some rifles, you are just going to look foolish. It's a pretty well known fact. Add a little additional buffer weight behind it to slow down the unlocking to allow the case to fully contract and release friction from the chamber wall.

I'm driving and I don't even have my glasses on.So I probably didn't even read that right.Either way, i'm just happy to say that i'm not having any issues.And everything is working flawlessly


Brass looks fantastic.I have a brass catcher on all my rifles.I don't even let them hit the ground

 

[JR1200W3]

I do understand the premature extraction concept; I just wasn't sure if that was what is causing the swipes and burrs; I just needed that confirmation. I think I'm at a 5oz buffer now, I cant remember but I will check when I get home. I'm just wondering what the weight threshold was, for when your gas blocks all the way down to where the carrier just locks up when empty, and you're running a 5oz buffer and you're still getting the swipes and burrs. Do we still keep going up in buffer weight? I kind of felt like that 5 was the max. I was also a little confused on if you're gas is already as low as it can get, and your buffers pretty heavy, and then you add even more buffer, now the gas is going to have to get raised back up a little to move that extra mass; wont that put you right back where you were when the gas was 2 clicks tighter and .2-.3oz lighter in the buffer?

Maybe this will help explain it. When I am using adjustable gas blocks that have a click detent adjustment like the SLR Sentry 7 versus an infinite fine tune like the seekins adjustable gas block that just uses a grub screw, I find that one unit of adjustment or one click on that gas block can be the difference between functioning and not functioning. But I can go up one step in buffer weight adjustment and achieve a more moderate level of bolt carrier speed without affecting whether the gun runs or not. Long winded way of saying buffer weight can offer a finer level of adjustment than the gas block depending on what parts you're using. So to put that in context, you really need to start with your gas block adjustment and then just fine-tune with small buffer weight adjustments.

So I am hesitant to say, " yeah man just keep going up and weight" because you haven't clarified if you've tried to fix the problem with your gas adjustment yet. I would focus a lot less on buying more buffers and swapping buffers out than I would by just trying to fix the problem at the gas port. That should be your #1 fix and then just consider that you MAY be able slow down the unlocking a little bit with a buffer adjustment once you are already 90% in the ball park with the gas setting.

I think you ask what weight buffer I'm using for a gas block setting. I couldn't tell you and even if I could, I wouldn't expect that to be transferrable across multiple rifles with varying barrel lengths, gas lengths, port size, suppressors, and load data.

 

[Basic user]

No I get it entirely. And that's what I ended up doing; I use superlative arms blocks exclusively on my builds, so I just clicked er down till she barely locked back then gave it one more click. still had the problems so I added some tungsten to the buffer so now I believe its about 5 ounces. Added a jp high pressure bolt as well. I still have to shoot it with full pressure loads to see if its still tearing up the extractor rim and leaving swipes on the case head. Thank you for all the explanation thus far. I appreciate it.

 

[JR1200W3]

No I get it entirely. And that's what I ended up doing; I use superlative arms blocks exclusively on my builds, so I just clicked er down till she barely locked back then gave it one more click. still had the problems so I added some tungsten to the buffer so now I believe its about 5 ounces. Added a jp high pressure bolt as well. I still have to shoot it with full pressure loads to see if its still tearing up the extractor rim and leaving swipes on the case head. Thank you for all the explanation thus far. I appreciate it.

No problem. The other thing to keep in mind is that gas guns just won't tolerate chamber pressure like a boat gun. And so you could get some ejector smearing and brass tearing simply because you're running high pressure. Beyond proper gassing and buffering.

 

[padom]

No problem. The other thing to keep in mind is that gas guns just won't tolerate chamber pressure like a boat gun. And so you could get some ejector smearing and brass tearing simply because you're running high pressure. Beyond proper gassing and buffering.

This is a good point. Handloading for 6.5cm gas gun are not your same loads as a 6.5cm bolt gun. And if shooting factory ammo that isnt gas gun specific, I have seen a lot of factory ammo cause blown primers and torn up cases in gassers....

I dont chase speed, accuracy over velocity all day long. Find yourself a super accurate, smooth shooting load and get your dope.