AR 10 and extractor issues (damaged brass)

[TexasHaag]

New to the AR10 (308 & 6.5c) A good percentage of the brass has damage to the case from the extractor. The extractor spring is supported by a rubber bumper/insert, that make it very tough to flex. The M16's I trained with (retired Army) only had a spring. All brass has been full length sized, checked in head space gauge (after size and tumble and after bullet is seated). I've dropped each round into the chamber with no resistance in or out.

Any suggestions?

Remove the bumper? and try it?

thanks!
Lee

 

[Hobo Hilton]

Photos of brass ?

 

[Jgault]

New to the AR10 (308 & 6.5c) A good percentage of the brass has damage to the case from the extractor. The extractor spring is supported by a rubber bumper/insert, that make it very tough to flex. The M16's I trained with (retired Army) only had a spring. All brass has been full length sized, checked in head space gauge (after size and tumble and after bullet is seated). I've dropped each round into the chamber with no resistance in or out.

Any suggestions?

Remove the bumper? and try it?

thanks!
Lee

Without seeing pictures not sure, but I will say 308 ar’s are allot harder on brass than a 5.56. The extractors on 308’s have considerably more tension just as a standard, with some 308 extractor setups having a almost death grip. The extractor itself probably isn’t the issue, it sounds more like dwell time and the case is still fully expanded when the bcg is extracting the shell.

 

[BullGear]

I would expect the gun manufacturer has tested the rubber bumper, so I don't believe that's you issue. Is the extractor ripping the brass? Like others have said, a picture of the brass would help us. It could also be a tight chamber too.

Pictures please.

 

[newguy2k3v2]

Are the rims pulled? It’s probably more of a gas/mass/timing issue than an extractor problem.

 

[Hobo Hilton]

I have been having a thought, in the back of my head for the past year or so. This is a good place to throw it out for discussion. Not to side track this discussion but to simply add to these issues.

Is the "base metal" used in cartridges being diluted by adding cheaper metal ?

Without a Brinell Hardness test machine, how will this be determined. A Chromatograph test would be nice but few people have access to that machine. Everything is being cheapened... Food, metals, medications, etc

Thoughts ?

Cartridge brass

30% zinc brass with good cold-working properties; used for ammunition cases

Brass Alloys: Their Chemical Compositions and Uses

This is a list of the common brass alloys, including their chemical compositions and their uses.

www.thoughtco.com

 

[TexasHaag]

Without seeing pictures not sure, but I will say 308 ar’s are allot harder on brass than a 5.56. The extractors on 308’s have considerably more tension just as a standard, with some 308 extractor setups having a almost death grip. The extractor itself probably isn’t the issue, it sounds more like dwell time and the case is still fully expanded when the bcg is extracting the shell.

Without seeing pictures not sure, but I will say 308 ar’s are allot harder on brass than a 5.56. The extractors on 308’s have considerably more tension just as a standard, with some 308 extractor setups having a almost death grip. The extractor itself probably isn’t the issue, it sounds more like dwell time and the case is still fully expanded when the bcg is extracting the shell.

Is the "dwell time" a gas issue?

 

[TexasHaag]

Are the rims pulled? It’s probably more of a gas/mass/timing issue than an extractor problem.

yes the rims are pulled slightly out of level with the rest of the case rim. The face of the rim has an indent right at the top.

 

[Jgault]

Is the "dwell time" a gas issue?

Gas and buffer weight. Basically the shell expands when fired becoming momentarily very tight in the chamber, if the bcg starts it backward travel to fast it’s pulling the shell before it has a chance to start returning to it’s normal size. You can reduce the gas but you might need a heavier buffer, the heavier buffer gives the bcg a few milliseconds delay because it’s pushing more weight.

 

[Jgault]

yes the rims are pulled slightly out of level with the rest of the case rim. The face of the rim has an indent right at the top.

There is a easy way to rule a few things out. Take the firing pin out of the bcg. Load a mag then manually cycle through it with the charging handle. Do the rounds cycle and easily? If they take force to remove with the charging handle the chamber might be a little tight or have buildup or a rough area. Look at the brass, was there rim damage cycling manually? The extractor will perform the same cycling manually or firing. The bent rim indicates the extractor is doing its job but having to pull a tight shell. If you can cycle normally with the charging handle it’s a buffer gas issue, if you can’t it’s more than likely a chamber issue.

 

[mtrmn]

You probably have one of those too-light buffers that seem to come as std issue in many .308 carbines.Your buffer needs to weigh app 5.4 ounces instead of the usual 3 ounces or so. You also need a dedicated spring that is rated for the recoil of the .308.

 

[TexasHaag]

You probably have one of those too-light buffers that seem to come as std issue in many .308 carbines.Your buffer needs to weigh app 5.4 ounces instead of the usual 3 ounces or so. You also need a dedicated spring that is rated for the recoil of the .308.

You probably have one of those too-light buffers that seem to come as std issue in many .308 carbines.Your buffer needs to weigh app 5.4 ounces instead of the usual 3 ounces or so. You also need a dedicated spring that is rated for the recoil of the .308.

The buffer is a JP Enterprises Silent Captured Spring, regular weight. I'm ordering 2 of the Tungsten weights and will try again.

 

[TexasHaag]

Gas and buffer weight. Basically the shell expands when fired becoming momentarily very tight in the chamber, if the bcg starts it backward travel to fast it’s pulling the shell before it has a chance to start returning to it’s normal size. You can reduce the gas but you might need a heavier buffer, the heavier buffer gives the bcg a few milliseconds delay because it’s pushing more weight.

I'll up the weight on the JP Enterprises Captured spring buffer. before I tweak the gas.

 

[B y r o n]

New to the AR10 (308 & 6.5c) A good percentage of the brass has damage to the case from the extractor. The extractor spring is supported by a rubber bumper/insert, that make it very tough to flex. The M16's I trained with (retired Army) only had a spring. All brass has been full length sized, checked in head space gauge (after size and tumble and after bullet is seated). I've dropped each round into the chamber with no resistance in or out.

Any suggestions?

Remove the bumper? and try it?

thanks!
Lee

So what is the rifle configuration? What caliber, what length barrel, rifle or carbine stock?

 

[TexasHaag]

So what is the rifle configuration? What caliber, what length barrel, rifle or carbine stock?

AR 10 .308 20" barrel, rifle stock

 

[Precision Underground]

I'll up the weight on the JP Enterprises Captured spring buffer. before I tweak the gas.

I would be turning the gas down as step one, assuming you have that ability. Heavier buffer may help but if it’s pulling the rim that hard it’s prob pulling it while the case is still expanded in the chamber; pulling it too hard too early. Less gas down the tube would be the fix IMO. You’ll get dents in the top of the case that’s pretty common for a large frame. Ours is tuned to run very soft and smooth and it still dents them sometimes.

 

[bfoosh006]

Make sure the portion of the extractor, that rides over the case rim, is reasonable smooth. If you polish the portion that slips over the rim... make sure not to touch the "claw" .

You do have the spacer installed for the rifle length buffer tube ... just checking.

What specific brand barrel ? And RLGS ? ( trying to "guesstimate" gas port size )

And to be honest, I wouldn't be to afraid to go heavy with your buffer weights... my Large Frames, with various brand barrels and gas system lengths / all with adj. Gas Blocks set at 6 open of the available 15 to wide open, and while using a rifle length buffer setup....( whew, that is a mouth ful....) all use a 9.3oz 308 rifle buffer with a Tubbs 308 Flatwire recoil spring.

The carbine setups, both Armalite Pattern buffer tube length and DPMS Pattern use 5.4-5.2oz buffer weights.

Dependent on your results with a heavier buffer weight... you might consider and adj. GB.

Limiting the cyclic speed, even by a few milliseconds, as mentioned above, will dramatically reduce brass abuse.

As well as being easier on you , easier to stay on target, easier on the parts... etc.

 

[TexasHaag]

Make sure the portion of the extractor, that rides over the case rim, is reasonable smooth. If you polish the portion that slips over the rim... make sure not to touch the "claw" .

You do have the spacer installed for the rifle length buffer tube ... just checking.

What specific brand barrel ? And RLGS ? ( trying to "guesstimate" gas port size )

And to be honest, I wouldn't be to afraid to go heavy with your buffer weights... my Large Frames, with various brand barrels and gas system lengths / all with adj. Gas Blocks set at 6 open of the available 15 to wide open, and while using a rifle length buffer setup....( whew, that is a mouth ful....) all use a 9.3oz 308 rifle buffer with a Tubbs 308 Flatwire recoil spring.

The carbine setups, both Armalite Pattern buffer tube length and DPMS Pattern use 5.4-5.2oz buffer weights.

Dependent on your results with a heavier buffer weight... you might consider and adj. GB.

Limiting the cyclic speed, even by a few milliseconds, as mentioned above, will dramatically reduce brass abuse.

As well as being easier on you , easier to stay on target, easier on the parts... etc.

Thanks, I'll inspect the extractor more closely. yes I used the spacer... The barrel is a .308 Wilson Combat 20" stainless, fluted with the same brand gas block and tube, it is adjustable, I'll bet the block is near closed, because the recoil seems a bit much for my beginning loads. The JP buffer is a AR10 buffer, standard weight. I've ordered a couple tungsten weights to change them out.

 

[bfoosh006]

Thanks, I'll inspect the extractor more closely. yes I used the spacer... The barrel is a .308 Wilson Combat 20" stainless, fluted with the same brand gas block and tube, it is adjustable, I'll bet the block is near closed, because the recoil seems a bit much for my beginning loads. The JP buffer is a AR10 buffer, standard weight. I've ordered a couple tungsten weights to change them out.

It sounds like it is open to far... IE, allowing to much gas flow.
If it was closed to much, the rifle would barely cycle.

Which specific Adj. GB from Wilson Combat, a quick look and I saw 3 different ones.

 

[HCICVOGT]

@TexasHaag I have the same barrel and buffer combo but different gas block. I'm also shooting with a can. What was the final fix? I'm ripping the rim of the case completely off. Did adding more weight to the buffer fix this issue for you?

 

[SalomonQST99]

I'll up the weight on the JP Enterprises Captured spring buffer. before I tweak the gas.

I have the same buffer in my 20" AR10 (JP JPSCS2-10). You really don't need to adjust the buffer, but work with the gas. Playing with the gas is much easier than trying to right size the buffer weight IMHO.

Since these are hand loads, are they close to max powder?

 

[mettee]

The buffer is a JP Enterprises Silent Captured Spring, regular weight. I'm ordering 2 of the Tungsten weights and will try again.

You will need at least 8.5 oz along with gas setting changes. Do they have XP springs for the silent capture system?

Is your receiver extension rifle length? The combination that has worked the best for me is a 7-5/8" receiver extension with a rifle length spring and the slash xh buffer. I'm not sure the JP SCS can carry enough weight to make 8+ oz.

 

[tucaz]

Thanks, I'll inspect the extractor more closely. yes I used the spacer... The barrel is a .308 Wilson Combat 20" stainless, fluted with the same brand gas block and tube, it is adjustable, I'll bet the block is near closed, because the recoil seems a bit much for my beginning loads. The JP buffer is a AR10 buffer, standard weight. I've ordered a couple tungsten weights to change them out.

the way i tune adjustable gas AR’s is to put one round in a mag, dial the gas back so it fails to lock open. then open the gas block so that it locks back every time. then one or 2 clicks open just to be sure.

basically just enough gas to reliably lock back everytime with your ammo.

i have a sig 716i 308 that is a little heavy on gas and bending rims. need to put my adjustable in it soon

i’m using a rifle length tube, sprinco 308 spring and a 308 rifle buffer that i put 2 tungsten weights in.

it drops cases at about 3-4 oclock but still feels gassy and is banding rims. i’m a lefty and half the time cases bounce off my ear pro!