Hot loads in AR-10s

[Mumbles]

I've always been taught that M1A/M14s should be fed lighter or lower charged loads due to wear on moving parts and specifically Op-Rods. I haven't heard much one way or the other on any other semi-autos, probably because FALs and such aren't generally used in the same way M-21 and such are.

What about AR-10s (and other .308 ARs). Does the design lend itself to handing more agressive loads any better than an M1A? Are there specific areas that are particularly vulnerable to abuse, like the M14's op-rod? It seems (to me) that at the very least, the upper receiver is a little better designed for absorbing the bolt's movement.

 

[FLIGHT762]

In my SR-25, I cannot get near the loads I use in my bolt guns. I have to load 1-2 grains lower or I blow primer pockets. That's my experience with this rifle. Near max loads beats the shit out of the brass.

 

[Danco411]

Never had a problem. My best .308 load in my Mega is 45g Varger under a 175g SMK or A-Max. That is book max and quick enough to get the job done. Never blown a primer but I don't reload cases more than 4 times usually 3.

 

[sinister]

GI M1s and M14s with forged receivers and Springfield and Armscorp cast receivers do NOT do well with maximum-charge / slow burn rate powder long range loads. M14 op rods do NOT do well (even with vented gas plugs) due to piston impact (they can bend).

AR-10s (with some work, like an XH Heavy Buffer, a Tubb Carrier Weight system, a longer gas tube and relocated gas block, and the addition of an adjustable gas system) can help mitigate but not completely fix brass stretching.

The AR-10 / SR-25 bolt catch tends to break / fail if you use max charge loads and do not add some kind of remediation (heavy buffer, CWS, or adjustable gas).

 

[elfster1234]

same, you can't go too hot... you start going over 44grns and you risk blowing primer pockets. I personally try not to go over 43grns varget. I've also found that super high performance factory ammo is almost sure to get blown primer pockets on ar10's.

In my SR-25, I cannot get near the loads I use in my bolt guns. I have to load 1-2 grains lower or I blow primer pockets. That's my experience with this rifle. Near max loads beats the shit out of the brass.

 

[elfster1234]

also, BTW....... if you're only shooting at 100 to maybe 200yards, then there is not reason to go really hot (just easier on the rifle, brass, and can actually be more accurate at times)....... some of my best reloads is with 168amax with only 40.5grns varget when shooting at 200yards and under. It is when you start hitting 300yards and more you need to step up the charge a bit.

same, you can't go too hot... you start going over 44grns and you risk blowing primer pockets. I personally try not to go over 43grns varget. I've also found that super high performance factory ammo is almost sure to get blown primer pockets on ar10's.

 

[Mumbles]

Much appreciated all. I'm willing to gamble on a broken bolt catch, and I can live with short brass life. Just don't want to wind up with my MWS in the same condition as the M-14 Sinister posted.

What do you mean by Extra heavy buffer? As in, heavier than H3?

 

[Laseredge]

Slash's Heavy Buffers | Products

 

[sinister]

 

[Tactical22]

I don't have a whole lot of experience with high pressure loads, but I have noticed increased primer flow/flattening and the occasional blown primer with high pressure loads in my .308 AR. It was nothing I couldn't remedy with my adjustable gas block, though.

 

[pmclaine]

GI M1s and M14s with forged receivers and Springfield and Armscorp cast receivers do NOT do well with maximum-charge / slow burn rate powder long range loads. M14 op rods do NOT do well (even with vented gas plugs) due to piston impact (they can bend).

AR-10s (with some work, like an XH Heavy Buffer, a Tubb Carrier Weight system, a longer gas tube and relocated gas block, and the addition of an adjustable gas system) can help mitigate but not completely fix brass stretching.

The AR-10 / SR-25 bolt catch tends to break / fail if you use max charge loads and do not add some kind of remediation (heavy buffer, CWS, or adjustable gas).

...and a 6 digit Garand too. So sad.

Actually Garands in a certain serial range were annealed in the field due to cracking at the heel. The receiver heels were dipped in hot led to soften them and prevent the cracks. The condition was supposedly linked to firing rifle grenade charges. The annealed heel will show as a discoloration/two tone of the rear of the receiver. A repark does not cover the cosmetic change. I would think your Garand heel should show the field annealing process.

Perhaps your rifle was never annealed and it proves the historical accuracy of why that process was done. With your permission Id like to post the pics over at the CMP forum or some such as the research guys may be interested.

Note; Springfield Il M1 Garands start at 7M so this is not a Geneseo M1. I cant read the entire heel and dont know what the M1A serial numbers code is so if this is an M1A disregard the above.

 

[wilecoyote]

I've always been taught that M1A/M14s should be fed lighter or lower charged loads due to wear on moving parts and specifically Op-Rods. I haven't heard much one way or the other on any other semi-autos, probably because FALs and such aren't generally used in the same way M-21 and such are.

What about AR-10s (and other .308 ARs). Does the design lend itself to handing more agressive loads any better than an M1A? Are there specific areas that are particularly vulnerable to abuse, like the M14's op-rod? It seems (to me) that at the very least, the upper receiver is a little better designed for absorbing the bolt's movement.

FALs too ARE sensitive to slow burn powders: they are engineered to work in full or semi-auto with a 144/147/150 grainer, and they don't like anything slower than Vihtavuori 135 or really heavier bullets,in full or semi_a proper synthetic recoil buffer is available and advisable for them,anyway_ if needed (?), slower powders / heavier bullets can be tested with the shut-off valve closed, in the "grenade" mode,manually operated single shot_

 

[mtrmn]

I have a Slash heavy buffer in my old Bushmaster BAR10 20" (predecessor to RRA), and my max loads are 41.5 gr IMR4895 or TAC with 168 gr Nosler match bullets. 42 gr same powders with 145gr FMJs from Widener's. Any hotter and I see pressure signs rather quickly. Book max is around 45 gr if I recall correctly. My loads get the job done and are the most accurate with those bullets anyway.

 

[909er]

My friend uses 43.9g of R15 Alliant powder behind 175g SMKs. He told me they were hot for his bolt gun. I tried a few out and they blew the primers out and ruined the brass. Needless to say; I wont be using that load in my AR10 any more. I went home and looked into my load data books and found that combo was almost 10% OVER the MAX book load for that particular powder and bullet combo. His bolt gun is fine with it evidently, not my gas gun.

 

[909er]

By the way, that 43.9 grain R15 OVERLOAD was sending the bullet down the tube at 2700-2725 fps. I knew it was too hot when I saw those numbers. 22" long Krieger Heavy barrel.

 

[BCP]

If you want more velocity powders like 2000MR and CFE are the answer. They work well in everything I have tried them in.

 

[Mumbles]

I'm using RL17 right now because it's the only thing I've been able to find on the shelf that'll work for .308, ever since I ran out of IMR4895. I did find some positive accounts of people shooting it through longer barrels with heavy bullets, but I don't expect anything too excellent out of my 16" MWS. It is a slower burning powder though, which is half the reason I started this thread.

The other half of the reason is that eventually, I expect to be able to buy IMR4895 again, and wanted to get an idea of just how aggressive I could be with the loads in an AR-pattern rifle. I've only ever loaded for bolt guns in the past.

 

[cobravenom39]

43 grains of Varget under 147 grain pulldowns has worked rather well for me. I also run the Slash heavy buffer, which really helps with quick follow-up shots

 

[sinister]

Reloader 17 is a very slow powder in any 308. This may give you alternative powders for 150 to 175 grains:

 

[Unknown]

I shoot the same loads in my stock TRG22 as I do in a 24 inch barreled LR-308. I test for the load that gives the best accuracy out of both rifles, rather than having two different loads. I give up a tiny bit of accuracy, but oddly, I get about 15-20 more FPS out of the LR-308 with the same load.

175 SMK
LCD match brass
CCI BR2 primer
43.5 grains of Varget
2667 fps out of the LR 308
2650 out of the TRG22

 

[wfjames22]

25650 out df the TRG22

I bet the recoil is crazy

 

[Unknown]

Sorry I missed the typo..guilty of bad proof reading. For those who couldn't figure out the velocity, it is about 2650-2660 out of the TRG22, and averages 2667 out of the LR308..

 

[xhairs88]

same, you can't go too hot... you start going over 44grns and you risk blowing primer pockets. I personally try not to go over 43grns varget. I've also found that super high performance factory ammo is almost sure to get blown primer pockets on ar10's.

I can't even get close to 43gr of Varget without crazy pressure signs and have found that the AR10 is very hard on brass when compared to other rifles.

 

[wfjames22]

Sorry I missed the typo..guilty of bad proof reading. For those who couldn't figure out the velocity, it is about 2650-2660 out of the TRG22, and averages 2667 out of the LR308..

I had a pretty good handle on your velocity, even with the typo...just jerking your chain.

 

[Unknown]

I had a pretty good handle on your velocity, even with the typo...just jerking your chain.

No offense taken. I should have caught that. It is always better to man up to a screw up, than to prove idiocy by denying the obvious mistake. Ya caught me fair and square.