Heavy buffers & Brass

#5
232593 said:
I have a 26” barrel and rifle length gas system. 6.5 Creedmoor.

Thank you
Click to expand...
Ouch. I doubt you can fix that without a resorting to a new barrel. Your bolt is unlocking way to early and I doubt any amount of buffer weight will fix it. You can try to help out as best you can by going as heavy as you can find. Do they make 1lb buffers? 😂

Get a new barrel or cut that one down to 18-20” in length would be the correct action. You may have to enlarge the gas port if your rifle won’t cycle reliably after you cut it down. The super heavy buffers are expensive and I doubt it will solve your problem. Put that money into one of the options above.
 
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#7
What else have you tried? what are your other parts of the gas system? theres almost always a way but Its going to be a trial and error tuning the whole system. buffer/spring/adjustable gas.

the way I do it is change one thing at a time either spring or buffer and then go through different gas settings to see how it functions.

and you can put a piece of the fuzzy velcro on your deflector to help reduce the denting.
 
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#8
2aBaCa said:
What else have you tried? what are your other parts of the gas system? theres almost always a way but Its going to be a trial and error tuning the whole system. buffer/spring/adjustable gas.

the way I do it is change one thing at a time either spring or buffer and then go through different gas settings to see how it functions.

and you can put a piece of the fuzzy velcro on your deflector to help reduce the denting.
Click to expand...
I don’t get denting, but thank you for that Velcro trick. As far as I can tell it’s the extractor chewing up the base of the cartridge.
 
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#9
232593 said:
I don’t get denting, but thank you for that Velcro trick. As far as I can tell it’s the extractor chewing up the base of the cartridge.
Click to expand...
pics? that doesnt sound like it has anything to do with the gas system. ive seen where the little rubber O ring inside the extractor causes issues. most people just remove it.
 
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#10
2aBaCa said:
pics? that doesnt sound like it has anything to do with the gas system. ive seen where the little rubber O ring inside the extractor causes issues. most people just remove it.
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I won’t be able to post pics for a few hours. It kind of looks like a cut in the base of the case. I am two grains below max powder charge.
 
#11
2aBaCa said:
pics? that doesnt sound like it has anything to do with the gas system. ive seen where the little rubber O ring inside the extractor causes issues. most people just remove it.
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Its extracting far to early because of the gas system. I’m not sure the buffer can be weighted enough to fix that issue with a 26” creedmoor barrel with a rifle length port.
 
#12
wade2big said:
Its extracting far to early because of the gas system. I’m not sure the buffer can be weighted enough to fix that issue with a 26” creedmoor barrel with a rifle length port.
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it's possible. but if its marks from ripping the case out like you say then it sounds like an excessive gas problem. adjustable gas block would help that.

I have a rifle length on a 6.5cm and run a low mass carrier and light SCS. gas is set at about 7/15 on an SLR.
 
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#13
2aBaCa said:
it's possible. but if its marks from ripping the case out like you say then it sounds like an excessive gas problem. adjustable gas block would help that.

I have a rifle length on a 6.5cm and run a low mass carrier and light SCS. gas is set at about 7/15 on an SLR.
Click to expand...
An adjustable gasblock doesn’t help timing. That’s why there are different gas port locations from carbine up to plus three. Plus 2 gas on 20” barrels is common. What length barrel do you have?
 
#16
wade2big said:
I said he could cut it to 18”-20” as well. The gas length is wrong.
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i dont see how the length of barrel effects timing. ive always operated on the notion port position effects timing and distance from port to end of barrel effects volume. 🤷‍♂️

if he's getting too much gas too soon . reducing gas will help keep the bcg in place for that millisecond longer and maybe enough for the case to shrink back down.
 
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#18
2aBaCa said:
i dont see how the length of barrel effects timing. ive always operated on the notion port position effects timing and distance from port to end of barrel effects volume. 🤷‍♂️

if he's getting too much gas too soon . reducing gas will help keep the bcg in place for that millisecond longer and maybe enough for the case to shrink back down.
Click to expand...
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”.
 
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#19
wade2big said:
Reducing gas flow by adjustable gasblock only helps with volume, not pressure at the port which is what is causing the OPs problem. There is a reason for longer gas lengths on the overbore cartridges. It’s why seekins moved away from the rifle length gas on their SP10 rifles. They were hard on brass and if a user run a suppressor, it was even worse. Daniel defense uses plus 1 on their 20”.
Click to expand...
yeah its better but they all used to be rifle length and it worked. It just took more tweaking. pressure and volume work together to operate the gas system and if you reduce one, you reduce the overall effect of both. If he has an over gass problem. He can adjust it to where his rifle needs thats the whole 26" to operate. isnt that the whole point of an adjustable gas block?

its not like he said he has a pistol length gas port on a 26" barrel at which point I would probably agree to replace it.
 
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#20
2aBaCa said:
yeah its better but they all used to be rifle length and it worked. It just took more tweaking. pressure and volume work together to operate the gas system and if you reduce one, you reduce the overall effect of both. If he has an over gass problem. He can adjust it to where his rifle needs thats the whole 26" to operate. isnt that the whole point of an adjustable gas block?

its not like he said he has a pistol length gas port on a 26" barrel at which point I would probably agree to replace it.
Click to expand...
No that isn’t the point of an adjustable gasblock. I though the same at one time as well. I’ll let someone with deeper understanding chime in.
 
#24
https://www.snipershide.com/shootin...-belted-magnum-problem.7112215/#post-10044682
Evintos said:
Unlocking timing is a combo of gas port pressure, dwell time, gas flow volume, overall system mass, gas efficiency, cam pin travel path/timing, ammunition pressure curve.

There is minimum volume of gas necessary to initial unlock. If there isn't enough dwell time, the gas vents out into the atmosphere before the BCG receives enough volume of gas. Too much dwell time and you have a excessive gas volume issue. The amount of gas flowing into the BCG exceeds the minimum required to start unlocking and it does so before excess gas vents out of the bore. The amount of volume of gas necessary is determined by how efficient your gas system is (leaky BCG? worn gas rings?) as well as the initial starting mass (semi-auto BCG, full auto BCG, low mass BCG, buffer weight), and necessary energy to compress a spring (the buffer spring plays more of a role in returning the mass back into battery).

If the gas port pressure is too high, the minimum gas volume reaches the BCG too fast starting the unlock cycle too early as well as introducing higher pressure gas that increases strain on various parts such as the bolt. If port pressures are too low, the gas doesn't flow back to the BCG faster than the bullet leaves the barrel leading to no unlock or partial unlock.

Position of the gas port relative to the chamber (pressure), gas port position relative to the muzzle (dwell), gas port diameter (constriction) determine the overall flow rate and pressure. All 3 have to be balanced properly according to the ammunition pressure curve in order to achieve proper timing.

Cam pin travel path is somewhat standardized (although there are a couple of BCGs with extended cam paths) but this dictates bolt rotational unlock speed. As the bolt carrier moves backwards, the cam pin moves along its path which allows the bolt to rotate to unlock.

Ejection pattern is determined by proper extractor tension, ejector rebound and BCG position and movement speed. BCG movement speed and position is determined by how fast the gas flow reaches the BCG and at what intensity (pressure).

If the BCG is cycling too fast, the brass in the chamber doesn't contract far enough to extract out of the chamber and when it returns forward it can attempt to load the next round in the magazine causing a double feed. If the BCG is traveling fast enough but in the overgassed condition, the brass ejects with more force into the brass deflector and this causes it to bounce forward resulting in a 1-2 o'clock ejection pattern. You can also experience even more issues on really overgassed situations such as bolt over base which is brass ejects, bounces off brass deflector but the the BCG returns forward faster than the magazine can push the next round upwards to load.

If the BCG is cycling too slow, it doesn't have enough energy to pull the brass back far enough to clear the ejection port and the brass gets kicked off the extractor claw back into the upper receiver which can cause issues like stovepipes or failures to extract. If the BCG is moving slow enough but far enough to clear the ejection port, the brass bounces off the brass deflector "softly" and this leads to a 3-4 o'clock ejection pattern.

It's a balance.

(I'll probably have to go back and edit something, too tired to proofread.)
Click to expand...
https://www.snipershide.com/shootin...-belted-magnum-problem.7112215/#post-10045692
LRRPF52 said:
Cyclic rate is determined by multiple factors:

Propellant mass (how much powder)
Burn rate
Bore volume
Gas port location
Gas port diameter
Gas block fitment to the journal
Gas tube fitment to the block
Carrier key ID relative to the gas tube flange
Internal carrier bore dimensions relative to the bolt

Projectile mass
Projectile bearing surface engagement with the rifling
Plug dwell time (the amount of time the projectile spends forward of the gas port in a pressure-accumulated state, which can and does include suppressors)

Reciprocating mass (BCG, buffer)
Action spring weight
Coefficient of friction on any articulating surfaces (new BCG rails with rough textured rails are draggier than worn smooth rails, thick lubrication sustains longer and more consistent low friction)
Tightness of the upper receiver carrier raceway relative to the Outer Diameter of the carrier rails (some companies have made tight raceways and/or oversized carrier rail ODs)
Chamber surface texture relative to extraction (smooth allows faster extraction, rough holds onto the case longer)

Ejection pattern isn’t a reliable method for diagnosing cyclic rate but can be an indicator if all the other components in the action are correctly-made (rare).

Extractor lip corner edges and angles on the spent brass deflector can change the ejection pattern on a system that is otherwise properly-gassed.

The more you look at it, the more you start to realize how important following a well-vetted Technical Data Package is, based on extensive pyramid testing if possible.
Click to expand...

Most likely -
A 26" rifle length gas system barrel is essentially a situation where you potentially have excessive gas issues due to the duration of gas returning to your operating system is way too long. Large frame AR platforms do have a tendency to leave marks on brass cases even when properly timed though, so a picture of the case will help to figure some things out.

Your options are essentially (if it's a timing issue)-
  1. Constrict gas port via restrictive AGB or constricted gas tube (BRT EZTune) (decreasing gas flow rate)
  2. Increase the minimum volume of gas (energy) necessary to cycle the system (increase buffer mass and/or spring strength, might go as far as using buffer weights designed for 9mm blowback AR PCCs)
  3. Reduce dwell time which is reducing gas flow duration (via barrel length shortening or get new barrel),
  4. choose a different powder that gives a different ammunition pressure curve (difficult without knowing what the pressure curve looks like)
  5. combination of the options.
The simplest of options to try (and is easily reversible) is increase buffer mass and spring strength (example - Sprinco orange + H3 (5.4oz) or heavier buffer)
 
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#25
Evintos said:
The simplest of options to try (and is easily reversible) is increase buffer mass and spring strength (example - Sprinco orange + H3 (5.4oz) or heavier buffer)
Click to expand...

This^^^and a adjustable gas block might help. I agree though, a +2 port makes a lot more sense on a 26” barrel. Let us know how it works out and please post pics.
 
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#26
ballisticdaddy said:
Have had good luck running the Lantac E-BCG and made a big difference on brass damage even shooting suppressed.
Click to expand...
During my break I called Lantac up and asked about that. They also said my barrel headspace may be too short. However my fired brass does not measure any shorter than that of my other AR10 in 6.5.
 
#27
2aBaCa said:
Yeah we may not even be barking up the right tree marks on brass is pretty vague
Click to expand...
Here are the pics of the brass. The damage is on the left side
3B31E3A3-B52C-4708-92FA-250934A56147.jpeg
AE176046-BB0D-4B20-B404-943046BCD644.jpeg
 
#31
Thats a gnarly ejector smear. The bolt is definitely unlocking too early. I bet that piece of brass wouldn’t fit in a shell holder without filing down the ledge. My friend has a 20” rifle length and his does that with a suppressor attached. His lower has the lighter and shorter .308 buffer that fits in carbine length receiver extensions.

Weight up the buffer and use an adjustable gas block and if that doesn’t help then read post #5.
 
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#32
wade2big said:
Thats a gnarly ejector smear. The bolt is definitely unlocking too early. I bet that piece of brass wouldn’t fit in a shell holder without filing down the ledge. My friend has a 20” rifle length and his does that with a suppressor attached. His lower has the lighter and shorter .308 buffer that fits in carbine length receiver extensions.

Weight up the buffer and use an adjustable gas block and if that doesn’t help then read post #5.
Click to expand...
Will do thank you. I’ll start with the buffer first. Is the company “heavy buffers” any good?
 
#33
wade2big said:
Thats a gnarly ejector smear. The bolt is definitely unlocking too early. I bet that piece of brass wouldn’t fit in a shell holder without filing down the ledge. My friend has a 20” rifle length and his does that with a suppressor attached. His lower has the lighter and shorter .308 buffer that fits in carbine length receiver extensions.

Weight up the buffer and use an adjustable gas block and if that doesn’t help then read post #5.
Click to expand...
What Wade said and break out a file.
 
#34
Thank you everybody for all the help. It’s greatly appreciated.

I was hoping with this 26” barrel I could get a bit more speed so I could meet my requirements for this platform. Hopefully with these recommendations I can do that.

Again thank you, and if there are more tips I’m all ears.
 
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#37
232593 said:
Will do thank you. I’ll start with the buffer first. Is the company “heavy buffers” any good?
Click to expand...
Brass indicates you're overgassed.

If you're referencing heavybuffers.com aka "Slash's heavy buffers", they're good to go.

Before you order though, you need to figure out what your current buffer weighs in at. If you're running a H/H1, you got some room to attempt an H2 or H3 (most likely H3) before you have to resort to something heavier. If you're already at H3, you're gonna want to go with the Slash's. If you go too heavy with the buffer, you'll end up with short stroke cycling issues.

You'll also want to double check compatibility with your buffer tube (stroke length reasons).
Sometimes it's best to order multiple buffers in various weights in case you ever run into cycling issues again due to changes in ammo/powder or adding a suppressor or changes in environmental conditions. Having multiple buffers in various weights allow you to tune the unlock timing to the conditions. Summer temps leaving you over gassed? Pop in a heavier buffer. Winter temps leaving you under gassed and short stroking? Pop in a lighter buffer. So on and so forth.

If you want to avoid having a bunch of buffers then an adjustable gas block is the solution.
 
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#38
Evintos said:
Brass indicates you're overgassed.

If you're referencing heavybuffers.com aka "Slash's heavy buffers", they're good to go.

Before you order though, you need to figure out what your current buffer weighs in at. If you're running a H/H1, you got some room to attempt an H2 or H3 (most likely H3) before you have to resort to something heavier. If you're already at H3, you're gonna want to go with the Slash's. If you go too heavy with the buffer, you'll end up with short stroke cycling issues.

You'll also want to double check compatibility with your buffer tube (stroke length reasons).
Sometimes it's best to order multiple buffers in various weights in case you ever run into cycling issues again due to changes in ammo/powder or adding a suppressor or changes in environmental conditions. Having multiple buffers in various weights allow you to tune the unlock timing to the conditions. Summer temps leaving you over gassed? Pop in a heavier buffer. Winter temps leaving you under gassed and short stroking? Pop in a lighter buffer. So on and so forth.

If you want to avoid having a bunch of buffers then an adjustable gas block is the solution.
Click to expand...
Thank you, have any adjustable gas blocks that you like more than others?
 
#39
232593 said:
Thank you, have any adjustable gas blocks that you like more than others?
Click to expand...
No strong preference other than clamp on with click detent. Don't like dimpling barrels nor infinite adjustable gas blocks. Infinite adjustable gas blocks screws seize very quickly and is more of a set and forget type of deal.
Click detent allows me to fiddle with gas settings based on changing conditions. SLR Sentry and Superlative in my experience is good to go. I don't have enough rounds through the Wojtek Arkto to confidently recommend it but so far so good.

- SLR Sentry - 15 positions
- Superlative Arms AGB - 18 positions in restrictive mode, I don't use the bleed off (28 positions in bleed off) since I prefer excess gas to propel my bullet rather than being bled off into the atmosphere
- Wojtek Arkto - 24 positions

The more positions/clicks, the finer the increment of tune you can achieve. On a few of my low mass AR builds, I've found myself wanting an in between click setting for the SLR Sentry and Superlative Arms.

However for most of my standard mass builds I haven't found myself wanting finer increment adjustment.

Preventative maintenance for all 3 gas blocks for me at the end of the range day is to turn the gas adjustment back and forth to "break loose" any carbon build up on the adjustment screw. Haven't had a stuck adjustment screw yet.
 
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#40
Is this your first AR10/LR308?

What are the load/powder/bullet specs for your round?

What is the BTO (Base To Ogive) measurement? How far is your bullet jumping to the lands? It’s not jammed is it?

I’m assuming this is a SAAMI spec chamber?

I’m assuming the BCG/ejector is fairly new?
 
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#41
Earnhardt said:
Is this your first AR10/LR308?

What are the load/powder/bullet specs for your round?

What is the BTO (Base To Ogive) measurement? How far is your bullet jumping to the lands? It’s not jammed is it?

I’m assuming this is a SAAMI spec chamber?

I’m assuming the BCG/ejector is fairly new?
Click to expand...
I have two other AR10s

I am using 135 grain ATIPS, STABAL, CCI MILSPEC Large Rifle Primers, and Peterson Brass loaded to mag length.

I don’t have my CBTOL data with me now. I can send it after I get home. I do know it is not jammed to the lands. I seated a bullet to the Hornady COAL in an empty case loaded it and extracted it and did not see any markings on the ogive.

it should be SAAMI spec chamber

BCG has 33 rounds through it
 
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#42
The brass that you posted a pic of…has it been cleaned in any form? (It looks fairly clean)
Or is that what it looked like after it was ejected?
Does the brass have “soot” on it after it’s ejected?
 
#43
232593 said:
Will a heavier buffer help keep brass from getting beat up on a 6.5 CM? I don’t run a can.

Thank you
Click to expand...
Yes. It slows the bolt-carrier down, which means it doesn't sling the brass as hard, so yes, it will help. Will it eliminate any wear, I doubt it, the design of the AR is naturally kind of hard on brass, but it will help eliminate beating it up like it is now and help reduce the damage.

I run H2 or H3 in just about all my AR's. After swapping to an H3 in my 10" .300 BLK it helped reduce visible wear on my brass noticeably. The case mouths stay round now (before they all had a slightly dented mouth from where they hit the metal deflector on the side of the receiver during ejection). Also, my brass doesn't get anywhere near as nasty with the suppressors on there, thanks to the extended unlock time before starting the ejection cycle.
 
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#44
I'm having the same type of damage on my 16" M&P10. Went to a Faxon 16" bbl(same AR10 carbine gas), JP SCSH2(heaviest setting/3 tungsten weights and also tried different springs) and Superlative AGB, BA BCG w/ FailZero bolt, and still have those marks. Switching to a Lancer eBCG helped a little(BCG was only switched due to the BA causing my trigger to bind up).

I have a 18" WC barrel coming in this weekend, so hopefully the longer dwell will make a difference.
 
#46
I'd had brand new BCG/ejectors give bad ejector swipes like that also...
It took a while for the ejector face to "smooth out" or wear in...
At first my 358 WSM KAK magnum ejectors were really bad... since they are not flat, but round like a BB, those rounded ejectors really tore the heck out of my brass at first

With how minimal the "soot" is on your brass, I don't think the pressure/blowback is really not that bad on your gun

I'll stand by my recommendation of:

9-10 oz Buffer, with Tubbs Flat Wire

Adjustable gas block

Toolcraft Double Ejector BCG with small firing pin
 
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#47
Earnhardt said:
I'd had brand new BCG/ejectors give bad ejector swipes like that also...
It took a while for the ejector face to "smooth out" or wear in...
At first my 358 WSM KAK magnum ejectors were really bad... since they are not flat, but round like a BB, those rounded ejectors really tore the heck out of my brass at first

With how minimal the "soot" is on your brass, I don't think the pressure/blowback is really that bad on your gun

I'll stand by my recommendation of:

9-10 oz Buffer, with Tubbs Flat Wire

Adjustable gas block

Toolcraft Double Ejector BCG with small firing pin
Click to expand...
Do you think the dual ejectors will make biggest difference?
 
#49
K2e2vin said:
Do you think the dual ejectors will make biggest difference?
Click to expand...
With what I see with his brass...yes

But regardless, the "Easy Button" for our large frame AR10/LR308 builds, is a 9-10 oz buffer with Tubbs Flat wire, adj gas block, and a standard weight BCG with at least a smaller firing pin, and even better double ejectors... and yes this is my opinion.

I've tried the "ultra light" titanium BCGs with a JP SCS set-up....and I still have those pieces to use
I just couldn't get the performance out of it that I thought the guns should have
 
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