Heavy buffers & Brass

I'm running 24" barrels on two of my LRs - a .243 Win shooting 95 grain bullets and a .308 Win. I get a little ejector swipe on the .243 Win but nothing that prevents me from reloading after inspection. The .243 has a rifle length gas tube, rifle length buffer spring, adjustable gas block, and a 9 oz buffer. It has a lighter buffer spring in it to reduce the forward impulse of the bolt cycling but the gas is turned down to compensate. The .308 has a rifle +2" gas tube, adjustable gas block, A5 buffer tube, light(er) buffer spring, and a 9 oz buffer. I get no ejector swipe from the .308.

My recommendation is to put a heavy buffer in it, adjust your gas to the least necessary to reliably lock your bolt back on an empty mag, and run the shit out of it. You can replace your rifle length buffer weights with tungsten weights - will cost you about $70, you'll need two packs of three each - https://www.eabco.net/EABCO-Tungsten-Buffer-Weights-fit-AR15-3-Pack_p_16097.html . I'd also full length resize your brass to .001-.002" short of your chamber length - keeping your cartridge tight in the chamber and up against the bolt face is a good thing. Not sure how powder selection would effect it - I'm running IMR 4895 which gives me a complete burn before the gas port in either rifles.
 
Last edited:
Kind of piggybacking this thread; but I'm reluctant to get rid of my JPSCS simply because I like the stock I'm using(carbine tube/Ruger RPR)...I put all tungsten weights and switched to the lightest spring they have(from "110" to "100"). Functions fine but brass ejected about 4 o'clock, but helped get rid of ejector swipe. I just threw on an 18" barrel with rifle gas system; should I throw the "110" spring back in there? I don't think that JPSCS can get anywhere near 10oz.
 
I have had good luck minimizing brass issues with heavier buffer weights and Adj. GB's.

My longest 6.5CM barrel is a 24" with a RLGS

YMMV , since we don't know your gas port size. ( no offense intended )

I would try a heavy buffer and a Adj. GB... I also would make sure the ejector is reasonably smooth at its edges.

Sorry if I missed it, what buffer tube length are you using ? And whose barrel.

Slash makes GTG products. I also use KAK buffers. And SLR Adj. GB's .

Adj. GB's can restrict the volume of the gas produced ( think hydrant fire house v. garden hose )
 
Last edited:
I have had good luck minimizing brass issues with heavier buffer weights and Adj. GB's.

My longest 6.5CM barrel is a 24" with a RLGS

YMMV , since we don't know your gas port size. ( no offense intended )

I would try a heavy buffer and a Adj. GB... I also would make sure the ejector is reasonably smooth at its edges.

Sorry if I missed it, what buffer tube length are you using ? And whose barrel.

Slash makes GTG products. I also use KAK buffers. And SLR Adj. GB's .

Adj. GB's can restrict the volume of the gas produced ( think hydrant fire house v. garden hose )
I have a Bartlein Barrel and a rifle length buffer tube. I’m traveling at present but when I get back I’m ordering a heavy buffer.
 
I have a Bartlein Barrel and a rifle length buffer tube. I’m traveling at present but when I get back I’m ordering a heavy buffer.
FWIW... I use a Tubbs 308 Flatwire recoil springs in all the various buffer tube lengths, and a KAK 9.3oz 308 buffer in the rifle length buffer tubes.
All my 308 / 6.5CM barrels ( various barrel lengths ) have gas port sizes that benefited from SLR adj. GB's and heavy buffer weights .... all of those are mid-length or rifle length gas systems. No + 1, 2" gas system lengths .

I do believe slowing the bolt unlocking, even slightly, helps with less brass abuse.

Only my Krieger 6.5CM barrel has ( IMHO ) a properly sized gas port. I would have to look up the actual size.

I have yet to see the need for a dedicated small firing pin hole BCG ( IE buying one to "fix" an issue ) ... however, I have seen the average firing pin hole sizes become smaller over the years.
The one BCG I have with dual ejectors, doesn't seem to offer any noticable benefit.
It is possible I have just been lucky with my setups.

FWIW... your pics look like fairly moderate casehead swipe. I have seen much worse on the internet.
I would try polishing / smoothing the ejector face edges, and the face of the extractor claw. Just the face, not the claw edges. That will allow a smoother snap over the rim. ( Only if needed. )

Please let us know your results, The Large Frame AR world can be a odd place.
 
Last edited:
Kind of piggybacking this thread; but I'm reluctant to get rid of my JPSCS simply because I like the stock I'm using(carbine tube/Ruger RPR)...I put all tungsten weights and switched to the lightest spring they have(from "110" to "100"). Functions fine but brass ejected about 4 o'clock, but helped get rid of ejector swipe. I just threw on an 18" barrel with rifle gas system; should I throw the "110" spring back in there? I don't think that JPSCS can get anywhere near 10oz.
Other way around. The stronger the spring (110 being the strongest JP has) and the more buffer mass, the closer towards 6 o'clock (towards the shooter) the brass will eject until short stroking (which occurs typically around the 5 o'clock ejection position).
So with a 100 spring, current 3 tungsten weight setup and 4 o'clock ejection, you're actually in the optimized zone and should leave it alone. The caveat to this is if you don't have an adjustable gas block and your winter temps get colder than when you tested your rifle, in which case you might want to lighten the mass on the SCS for reliability purposes.

If you want to tune it to have a better recoil impulse, you'd go up to 105 or 110 springs. Going up the spring weight may put you in the 4:30 position which is around the razor's edge of reliability or it may just straight up put you into a short stroke situation.

Your setup for a no messing around, no AGB for reliability would be something like a 2 tungsten, 1 steel, 100 spring which would give you closer to a 3 o'clock position ejection (straight to the right). If you want to fine tune it even more to try and aim for a 3:30 position (which would be a better blend of impulse feel and reliability), you'd do the 2 tungsten, 1 steel, either a 105 or 110 spring.

If you shoot both suppressed and unsuppressed, then you would have to choose a compromise tune.
 
  • Like
Reactions: K2e2vin and otnot
Reducing gas flow by adjustable gasblock only helps with volume, not pressure at the port which is what is causing the OPs problem. With a shorter barrel after the port, there would be less peak pressure for a shorter amount of time.

There is a reason for longer gas lengths on the overbore cartridges especially with longer barrels. It’s why seekins moved away from the rifle length gas on their SP10 rifles and went to a plus 2. They were hard on brass and if a user run a suppressor, it was even worse. Daniel defense uses plus 1 on their 20”.

Sorry, but you've given bad advice about this without a full understanding of how it works. My intent here is not to slam you, but to hopefully explain a more complete picture of what's going on and why gas flow restriction does work.

Pressure at the gas port is NOT the problem, or at least not the deciding factor as you seem to think. Pressure in the bolt carrier, and timing to reach that pressure, is what's important; the BCG requires a certain amount of gas pressure to overcome the force needed to unlock* and metering gas flow causes that pressure to build slower. A restriction of any kind (gas port size, AGB, etc) affects the rate that gas feeds back to the BCG, and therefore the timing before it unlocks.

This is not a static system, far from it; in a dynamic system like this the supply pressure (at the port) is only one factor in determining pressure in the final stage (the BCG). In a dynamic system, gas flow and pressure are directly related; restricting flow from a high pressure chamber to a low pressure chamber delays pressure buildup in the secondary chamber and can restrict the total pressure buildup if the system does not reach a static state.

*The force needed for unlocking is also dynamic and not a static number; as pressure drops in the chamber the necessary force also drops. Obviously the goal is to delay unlocking until that force is at it's lowest possible point while maintaining reliability.

All that to say, yeah he can fix the issue with gas adjustment. It doesn't do exactly the same thing as a longer gas system, because the pressure supply still begins earlier, but the gas flow can still be metered at a lower rate, limiting gas volume and pressure (which are directly related) at the BCG, and therefore unlock timing.
 
Last edited:
Sorry, but you've given bad advice about this without a full understanding of how it works. My intent here is not to slam you, but to hopefully explain a more complete picture of what's going on and why gas flow restriction does work.

Pressure at the gas port is NOT the problem, or at least not the deciding factor as you seem to think. Pressure in the bolt carrier, and timing to reach that pressure, is what's important; the BCG requires a certain amount of gas pressure to overcome the force needed to unlock* and metering gas flow causes that pressure to build slower. A restriction of any kind (gas port size, AGB, etc) affects the rate that gas feeds back to the BCG, and therefore the timing before it unlocks.

This is not a static system, far from it; in a dynamic system like this the supply pressure (at the port) is only one factor in determining pressure in the final stage (the BCG). In a dynamic system, gas flow and pressure are directly related; restricting flow from a high pressure chamber to a low pressure chamber delays pressure buildup in the secondary chamber and can restrict the total pressure buildup if the system does not reach a static state.

*The force needed for unlocking is also dynamic and not a static number; as pressure drops in the chamber the necessary force also drops. Obviously the goal is to delay unlocking until that force is at it's lowest possible point while maintaining reliability.

All that to say, yeah he can fix the issue with gas adjustment. It doesn't do exactly the same thing as a longer gas system, because the pressure supply still begins earlier, but the gas flow can still be metered at a lower rate, limiting gas volume and pressure (which are directly related) at the BCG, and therefore unlock timing.
I didn’t give incorrect advice. You are to a point. An adjustable gas block can help to some extent and the OP should be using one. The bolt can still unlock while there is far too much pressure in the chamber. Gas restriction can only does so much. Dwell time is a thing and the OP’s setup has far too much.

Let the guys that run suppressors chime in. They will tell you that you are incorrect as well. There isn’t an adjustable gas block made that would allow the OP’s setup to work with a suppressor. Moving the gas port towards the muzzle in addition to an adjustable gasblock will. This takes it to the extreme but that sometimes gets the point across better. To test your theory, try building a 26” 6.5cm with a carbine gas and use an adjustable gasblock to make it function correctly. Wouldn’t work even with a heavy buffer and spring. The bolt would not cycle and with one click more on the gasblock, it would cycle violently. All or nothing.

I’m not a AR mastermind by any means and I have lots to learn, but I have personal experience with what the OP is speaking of. Been there. That being said, an adjustable gasblock and an extremely heavy buffer and spring, may work for him considering he shoots unsurrpressed. He said he was going to try it so we will find out. It still doesn’t change the fact that his barrel is drilled with the incorrect gas port location.
 
Last edited:
If I could get a souped
I didn’t give incorrect advice at all. You did. An adjustable gas block can help to some extent and the OP should be using one. Let the guys that run suppressors chime in. They will tell you that you are incorrect. There isn’t an adjustable gas block made that would allow the OP’s setup to work with a suppressor. Moving the gas port towards the muzzle in addition to an adjustable gasblock will. This takes it to the extreme but that sometimes gets the point across better. Try building a 26” 6.5cm with a carbine gas and use an adjustable gasblock to make it function correctly. Wouldn’t work even with a heavy buffer and spring. The bolt will still unlock while there is far too much pressure in the chamber. Gas restriction can only does so much. Dwell time is a thing.

I’m not a AR mastermind by any means and I have lots to learn, but I have personal experience with what the OP is speaking of. Been there.
I built a 24" 45 Raptor with a mid-length gas system....because the barrel maker would ONLY drill a mid-length (long story)

I got that to work.
The longer the barrel, and the shorter the gas system, the more soot that was feeding back through the gas tube before the bullet uncorked

I then built a 24" 45 Raptor with a rifle gas system...way less back fed soot on the brass, and in the upper.

In my opinion, it not only depends on the cartridge you're shooting, but also the powder/bullet combo you are using.

In my 6.5 CM's, H4350/Reloder 16 are alot more user friendly than a round that has Reloder 26 in it.
The powder burn pressure curve is alot longer (not higher) in RL-26 than it is in H4350 and RL-16.

One of the best tools to see this with is Quickloads

Quickloads gives you an approximate pressure, in relation to how far the bullet has traveled down the barrel

This is very useful to us shooting large frame AR's.
Because it gives us a pretty good idea of what the pressure will be at the gas port with the various gas port lengths we use...mid, rifle, rifle +2, rifle +3..., in relation to the various calibers, powders, bullets we might be using.
 
  • Like
Reactions: Yondering
Long explanation below to expand peoples' understanding.

Suppressors on an AR (or any gas operated firearm) can be thought of as essentially extended barrel length that increases dwell time. With an AGB but with a restrictive gas port and extended dwell time, you restrict gas flow rate to compensate for extended dwell time. An AGB is essentially a variable gas port without actually drilling into a barrel or welding a gas port up.

Yes, there is backpressure but the backpressure isn't high enough to unlock the bolt (because it can't as it's not direct blowback) and it also isn't high enough to maintain the expanded state of the brass case. The bolt and barrel extension is not an airtight seal. So when the dwell time is increased, your brass can already be at a "contracted" state before your bullet leaves the barrel and this gas flow is in both directions, both pushing bullet forwards until it leaves the muzzle and continuing to leak around a contracted case and non-airtight bolt/barrel extension. This is why you also get soot on the shoulder and case neck of even suppressed bolt action firearms. To sum up, if the time it takes for the bullet to exit the barrel is longer than the time it takes for the brass case to contract, you will get soot on your case (suppressed or unsuppressed).

You can restrict so much gas flow to the point where your BCG doesn't even move rearward - eg. completely closing off the gas setting on an AGB, rendering the AR system a bolt action. You can do this if you want to test how loud a subsonic 300blk load actually is without action noise.

The gas rings on your bolt combined with the chamber inside of the bolt carrier creates one part of the minimum gas volume requirements. This is why the tail of your bolt has fouling on it and why the good gas rings are important, it's because of this chamber. The timing is essentially filling that chamber with enough gas to move the carrier which moves the hammer, compress hammer spring, move buffer, compress buffer spring, overcome friction, etc. The bolt itself cannot move rearwards or forwards much as it is trapped in the barrel extension unless it rotates so that the bolt lugs clears the barrel extension.

This is also why adjustable gas keys work. (Negatives with adjustable gas keys however is the seal between your gas tube and gas key is typically less tight than the seal between your gas block and barrel. As such, gas will leak a bit more around your gas key before the chamber fills.)

There are ports on the side of your bolt carrier (not found on piston ARs) that vent/leaks this gas out. If the gas flow cannot fill this chamber (the chamber volume grows larger as the carrier moves rearward) faster than the gas leak out, your BCG does not move rearward completely (resulting in partial unlocking). Once the minimum volume is reached, any excess gas flow that comes down the gas tube simply is wasted, it continues to fill the chamber (moving the BCG faster) until the gas key is far enough away from your gas tube, although during this time, all the excess gas is essentially vented everywhere inside your upper receiver.

Rearwards pressure on the bolt face itself without pressure moving the carrier only forces the bolt to lock even harder into the barrel extension. The rearward carrier movement is required in order for the bolt to rotate (via the linked cam pin/cam path).

Experiment - Remove BCG from upper, compress the bolt into the bolt carrier and then reassemble your upper, you'll find that your BCG does not go into the extension because the bolt rotational position is out of alignment. This alignment is what locks or unlocks your bolt into your extension. In order to reassemble, you have to put it in the unlocked position by extended the BCG.
Most people think of it as "extending" the bolt or "compressing" the bolt , but functionally, it's better to think of it as moving the carrier into the rearward position or forward position and that the bolt simply rotates in place.
When your bolt is locked hard (fouling, stuck case) into your extension (happens when gas volume into the BCG is not enough to overcome friction), your charging handle isn't applying rearward force to rotate and pull the bolt out of the extension, it's only applying rearward force onto your carrier so that the bolt which is connected to the carrier via cam pin in the cam path is forced to rotate as the carrier travels rearwards. If your cam pin path is blocked in this scenario, the system stays locked until that cam path clears.

*To sum it up, gas flow and gas restriction is a significant factor in a gas operated firearm. Dwell time is essentially the amount of time the gas flow is able to return to the BCG. Longer dwell = longer flow duration.

High flow rate + short duration = functional.
Low flow rate + long duration = also functional.
 
Last edited:
I didn’t give incorrect advice. You are to a point. An adjustable gas block can help to some extent and the OP should be using one. The bolt can still unlock while there is far too much pressure in the chamber. Gas restriction can only does so much. Dwell time is a thing and the OP’s setup has far too much.

Let the guys that run suppressors chime in. They will tell you that you are incorrect as well. There isn’t an adjustable gas block made that would allow the OP’s setup to work with a suppressor. Moving the gas port towards the muzzle in addition to an adjustable gasblock will. This takes it to the extreme but that sometimes gets the point across better. To test your theory, try building a 26” 6.5cm with a carbine gas and use an adjustable gasblock to make it function correctly. Wouldn’t work even with a heavy buffer and spring. The bolt would not cycle and with one click more on the gasblock, it would cycle violently. All or nothing.

I’m not a AR mastermind by any means and I have lots to learn, but I have personal experience with what the OP is speaking of. Been there. That being said, an adjustable gasblock and an extremely heavy buffer and spring, may work for him considering he shoots unsurrpressed. He said he was going to try it so we will find out. It still doesn’t change the fact that his barrel is drilled with the incorrect gas port location.

Buddy, you aren’t the only one with experience in this. Sounds like you don’t even use a suppressor; I’ve been using the them for years.

I get the impression you stopped reading after my first sentence and just reacted to that instead of the logic behind it.
 
Buddy, you aren’t the only one with experience in this. Sounds like you don’t even use a suppressor; I’ve been using the them for years.

I get the impression you stopped reading after my first sentence and just reacted to that instead of the logic behind it.
I read your post and you described what takes place well. You are just mistaken what an adjustable gasblock can do when the gas port location is so far from optimal as OP’s is. There is a reason that plus 1 and plus 2 ports are common starting at 20” in 6.5 creedmoor gas guns.
 
If I could get a souped

I built a 24" 45 Raptor with a mid-length gas system....because the barrel maker would ONLY drill a mid-length (long story)

I got that to work.
The longer the barrel, and the shorter the gas system, the more soot that was feeding back through the gas tube before the bullet uncorked

I then built a 24" 45 Raptor with a rifle gas system...way less back fed soot on the brass, and in the upper.

In my opinion, it not only depends on the cartridge you're shooting, but also the powder/bullet combo you are using.

In my 6.5 CM's, H4350/Reloder 16 are alot more user friendly than a round that has Reloder 26 in it.
The powder burn pressure curve is alot longer (not higher) in RL-26 than it is in H4350 and RL-16.

One of the best tools to see this with is Quickloads

Quickloads gives you an approximate pressure, in relation to how far the bullet has traveled down the barrel

This is very useful to us shooting large frame AR's.
Because it gives us a pretty good idea of what the pressure will be at the gas port with the various gas port lengths we use...mid, rifle, rifle +2, rifle +3..., in relation to the various calibers, powders, bullets we might be using.
I have a lot of H4350, but the problem is I don’t have many of the primers( fed 210ms) that make it really work great. So I’m stuck with CCI MILSPEC & STABAL. Unless I can use FED215ms & 205m(I have those in abundance) I’m pretty much stuck with what I have). So when I’m done traveling I’m going to first try that heavy buffer many have recommended.
 
Other way around. The stronger the spring (110 being the strongest JP has) and the more buffer mass, the closer towards 6 o'clock (towards the shooter) the brass will eject until short stroking (which occurs typically around the 5 o'clock ejection position).
So with a 100 spring, current 3 tungsten weight setup and 4 o'clock ejection, you're actually in the optimized zone and should leave it alone. The caveat to this is if you don't have an adjustable gas block and your winter temps get colder than when you tested your rifle, in which case you might want to lighten the mass on the SCS for reliability purposes.

If you want to tune it to have a better recoil impulse, you'd go up to 105 or 110 springs. Going up the spring weight may put you in the 4:30 position which is around the razor's edge of reliability or it may just straight up put you into a short stroke situation.

Your setup for a no messing around, no AGB for reliability would be something like a 2 tungsten, 1 steel, 100 spring which would give you closer to a 3 o'clock position ejection (straight to the right). If you want to fine tune it even more to try and aim for a 3:30 position (which would be a better blend of impulse feel and reliability), you'd do the 2 tungsten, 1 steel, either a 105 or 110 spring.

If you shoot both suppressed and unsuppressed, then you would have to choose a compromise tune.
Do you have a vendor that you recommend for the springs you mention?

Thank you
 
Do you have a vendor that you recommend for the springs you mention?

Thank you
That quote from me is a response to K2e2vin's post and his particular setup as he piggybacked onto your thread. Unless you have the exact situation as he does following it won't work for you.
If you do however have the same setup (which is a JP Silent Captured Spring with a 4 o'clock ejection pattern) then the springs can order direct from manufacturer. If you're tryin to save money, no clue which vendor has it on sale.

https://www.jprifles.com/buy.php?item=JPSCS-PACK10
If you're running a traditional buffer setup though, you'd use Sprinco brand Orange spring or Tubb Precision AR10 Flat Wire spring for spring tuning but mass tuning is the first step. If you don't want to buy a bunch of buffers and want to modify your current buffer, buy buffer components. You'd buy the internal tungsten, steel and aluminum to play with combos to get a weight that would get you to the ideal ejection before you fine tune the spring. You use a punch to drift out a roll pin on your buffer to remove and change out internal weights. But before you buy all this stuff, you got figure out what your current buffer weight is and go from there.

https://www.kakindustry.com/ar-15-p...ual-buffer-tube-parts/individual-buffer-parts
KAK Industry Black Friday code - FRIDAY15
 
  • Like
Reactions: 232593
Tested the heavy buffer. It seemed to reduce damage to the case at the 2820 FPS node and the 2850 FPS node I found last time

However I had several light primer strikes that required me to rechamber the round and fire it again. I was using the same CCI MILSPEC Large rifle primers as last time. Not sure if maybe a round was bouncing in the brass catcher and interfering with the bolt while in motion was causing it or not??? Last time I went out I had no light primer strikes only thing that changed was the addition of the heavy buffer.

Any of you get light primer strikes when you added a heavy buffer?
 
Did you make sure bcg was fully in battery? If it's cycling properly I don't see how a heavy buffer would cause any issues. Not sure if you're shooting outdoors but colder weather is making the oil/grease more viscous?
It was about 55 degrees out when I did the testing.

When I get extracted the round I saw a slight dent in the primer.

Could the heavy bolt cause issues getting the bolt to cycle properly?
 
The following could be potential issues.

- Cold temps plus lube on firing pin or lube inside the firing pin channel.
- Cold temps plus lube (typically grease) on hammer and hammer pin slowing down hammer swing
- Debris in firing pin channel
- Debris in barrel extension (causing incomplete return to battery)
- Weak hammer spring
- Broken hammer
- Inadequate firing pin protrusion (out of spec or from damage)
- Potential interference with brass catcher assuming it's attached to the receiver
- CCI primer duds (lots of reports on CCI primer issues with lot numbers produced in 2020 and 2021)
- Primer not seated deep enough

Buffers don't typically cause light primer strikes unless it's causing cycling issues. If the light primer strikes were on your first few rounds of your range trip when your rifle was "cold" and the following rounds after you've fired the few were normal, then I'd lean towards a lubricant issue.

Expanding a bit on the green: A change in buffer weight will typically cause a change in your ejection pattern and brass ejection force. A difference in how and in what direction your brass is now ejecting with the heavier buffer could necessitate moving your attached brass catcher to a different position to prevent interference with the complete cycling of the action, especially if it's causing your BCG to not fully return to battery.
 
  • Like
Reactions: iktomi and 232593
Tested the heavy buffer. It seemed to reduce damage to the case at the 2820 FPS node and the 2850 FPS node I found last time

However I had several light primer strikes that required me to rechamber the round and fire it again. I was using the same CCI MILSPEC Large rifle primers as last time. Not sure if maybe a round was bouncing in the brass catcher and interfering with the bolt while in motion was causing it or not??? Last time I went out I had no light primer strikes only thing that changed was the addition of the heavy buffer.

Any of you get light primer strikes when you added a heavy buffer?
So if I am understanding 24" barrel 6.5 creed with rifle length gas.
What weight bullet are you getting 2820 FPS?

The bottom line is you are wasting your time and money looking for BS solutions either get a +2 barrel or considerably
reduce your load .
 
So if I am understanding 24" barrel 6.5 creed with rifle length gas.
What weight bullet are you getting 2820 FPS?

The bottom line is you are wasting your time and money looking for BS solutions either get a +2 barrel or considerably
reduce your load .
He is shooting 135gr A-tips through a 26” rifle gas barrel. Still seems hot.
 
He is shooting 135gr A-tips through a 26” rifle gas barrel. Still seems hot.
I was using 42.5 grains of STABAL, Peterson brass, and CCI MILSPEC Primers with the 135 grain ATIPS. In the chronograph data I found that between 42.4-42.6 & 42.8-43.2 charge weights looked like potential stable loads so I tried 42.5 grains and 43 grains. 42.5 yielded an ES of 14 FPS (2820 average FPS) and sub MOA. 43 grains yielded 2853 FPS and slight damage to the brass.

Wouldn’t the extra barrel length safely yield extra velocity?

The gun has less than 50 rounds through it.
 
If it was a bolt rifle yes but not a gasser, that is why the Sierra manual
has 223 and a separate 223 Rem Bolt section.

EDit: Are you getting loose primer pockets?

A good tool to have is a gauge pin for your primer pockets
-.210 for Large and - .174 for small, if pin fits into the pocket brass is trash.
 
Last edited:
If it was a bolt rifle yes but not a gasser, that is why the Sierra manual
has 223 and a separate 223 Rem Bolt section.

EDit: Are you getting loose primer pockets?

A good tool to have is a gauge pin for your primer pockets
-.210 for Large and - .174 for small, if pin fits into the pocket brass is trash.
I have not deprimed the brass yet. Primers are not flattening out or cratering.

Will this gauge work
 
Tested the heavy buffer. It seemed to reduce damage to the case at the 2820 FPS node and the 2850 FPS node I found last time

However I had several light primer strikes that required me to rechamber the round and fire it again. I was using the same CCI MILSPEC Large rifle primers as last time. Not sure if maybe a round was bouncing in the brass catcher and interfering with the bolt while in motion was causing it or not??? Last time I went out I had no light primer strikes only thing that changed was the addition of the heavy buffer.

Any of you get light primer strikes when you added a heavy buffer?
What specific heavy buffer ? Could you "maybe" be experiencing some kind of bolt bounce ?
 
  • Like
Reactions: 232593
If it was a bolt rifle yes but not a gasser, that is why the Sierra manual
has 223 and a separate 223 Rem Bolt section.

EDit: Are you getting loose primer pockets?

A good tool to have is a gauge pin for your primer pockets
-.210 for Large and - .174 for small, if pin fits into the pocket brass is trash.
I ran that primer pocket gauge on some deprimed brass and the pockets were ok
 
Are those solid buffers or is their weights inside that are free to slide back and forth? This has nothing to do with your issue, I’m just curious.

May be worth contacting Clint at Heavy Buffers. The webpage does not mention if individual weights are used in the XH Rifle buffer. So it may in fact be solid. But it would seem that not having the free sliding weights would remove the "dead-blow" affect. Perhaps this is not an issue on rifle length systems.

Per Clint at Heavy Buffers, the XH "Carbine" buffer has tungsten weights in it.
"you can “mix-and-match“ the internal weights. Every tungsten weight you replace with a steel one will result in a net loss of about 1 ounce."
 
  • Like
Reactions: Earnhardt
I ran my 2850FPS load with the heavy buffer and had several light primer strikes. I took it out and put in the regular buffer and resumed testing with both the 2850FPS load and a few strings of H4350, I did not have a single light primer strike. I was using MAGPUL mags for my testing.
 
I ran my 2850FPS load with the heavy buffer and had several light primer strikes. I took it out and put in the regular buffer and resumed testing with both the 2850FPS load and a few strings of H4350, I did not have a single light primer strike. I was using MAGPUL mags for my testing.
What’s the adjustable gas block setting at?
 
I found that the superlative arms GB in bleed off range with a slightly heavy buffer works well for rifle length gas 6.5s.
I found the opposite in my Seekins w/ Proof CF 18” .308. I have read a lot of others saying that bleed off didn’t work well with 16-18” and rifle gas. I’ve went to 1.75-2 full turns open from the completely closed position worked much better and actually reduced plunger extractor marks considerably. Ejection position went from 1 o’clock to 3-3:30 position.

Fwiw, Tubbs flat spring, rifle buffer tube and 5.6 oz KAK “AR10” buffer, which is actually shorter than “AR15” buffers.
 
  • Like
Reactions: Yondering