AR-10 eating brass with a can installed

[spencerhenry]

I have an older AR-10, from around the year 2000. It ate brass bad years ago, Armalite said I shouldn't use reloads. That didn't work for me, I modified the gas block to be adjustable and fixed the issue. I didn't shoot it much for a few years, then I got it set up and working, but today it was not doing well. With just enough gas to cycle the action, I get ejector smears and blown primers. If I turn the gas down the brass looks great but it doesn't cycle. I tried without the can and no smears or blown primers. First round is usually good with the can, successive shots the brass gets hammered. Im running 42gr imr4895, which in this gun and in a bolt rifle produces one ragged hole at 100 yards.
Perhaps a different powder? Suggestions?

 

[jepp2]

First round is usually good with the can, successive shots the brass gets hammered. Im running 42gr imr4895,

Knowing the cartridge (I can guess 308 win) and bullet would be useful information.

 

[spencerhenry]

Oops, yes, 308. 168smk

 

[457ciSBC]

A change in gas dynamics with the suppressor installed is at work here, you need to negate the byproduct of excessive port pressure when the can is installed. Just to make sure we are on the same page; what the barrel and gas tube length? What spring and buffer type/length are you using? What is the coil count on your buffer spring? I assume it is a non lightweight bolt carrier?

 

[DGP4]

Try a faster burning powder. H335 works for me with a start at 39 grains.

 

[XTR]

Faster powder might help, but watch the pressure, or get an adjustable gas block and use a different setting with the can on.

I run a Superlative Arms on mine, I'm sure others will work. I run a load in that range with H4895.

 

[spencerhenry]

It is adjustable gas block.
24” barrel, I’ll have to check to see the buffer and spring. It’s all original.

 

[Txhillbilly]

Another vote on getting a Superlative Arms gas block. I ran other brands of adjustable gas blocks, but now all of my AR's large and small have Superlative gas blocks on them, and I have zero problems running my suppressor's on any of them.