Brass -, Yes,Steel No

[Duck0714]

Ihave an AR PSA DISSIPATOR 5.56 rifle that fires brass case ammo flawlessly but will fire the 1st hand charged round of streel case but will not pick up the next round. I have swapped the buffer and spring with same result. I have installed a PSA polished fire control set with extra power hammer spring. Any suggestions would be appreciated. Thanks.

 

[RandallC]

One thing to remember with steel casing is it does not expand and de-expand as well as brass. Now when the bolt comes back does it get stuck or bypass the next round?

I would try to add alittle more lube first and see what happens.

 

[Duck0714]

It bypasses the next round but does clock the hammer then dry fires.

 

[RandallC]

That’s strange, can you confirm the gas block is tight, it seems some people have had problems with that from psa.

 

[Duck0714]

I just tried on a completely different AR and same thing ,brass good steel no good. I'm beginning to think I have some bad steel case ammo.

 

[RandallC]

What brand ammo you get?

 

[Duck0714]

TUL-AMMO

 

[RandallC]

Try a different brand as well as mag. Tul-ammo is coated with something that may stop the round from chambering.

If the mag is a pmag try another one from
Magpul or another brand. If it is another brand try a different one and don’t put 30 in it put like 3-10 until it resolves.

Also have you cleaned and lubed the firearm, ar15s are suppose to be lubed before you shoot them with grease not oil.

 

[Duck0714]

These are brand new uppers with brand new BCG and I use D&H 30 rnd aluminum mags and usually only load 20 rounds in them. I have tried putting 5-6 rounds but still wont pick up the 2nd round. Since the same problem occurs with 2 completely different new AR's, I am almost positive it is the ammo. Thanks for your input.

 

[Duck0714]

I do have a Tapco polymer mag that I will try just to be sure. Thanks again.

 

[Joel6180]

Try with one - see if the bolt locks after firing. If so, try with two - see if bolt picks up and chambers 2nd round. Sounds to me like the steel is putting more drag on the bolt than the brass, and the bolt isn't coming back enough to pick up additional rounds.

 

[Duck0714]

OK, with the Tapco mag, with steel the bolt locks back but not all the way. Brass locks all the way back. Since the steel does not lock back all the way, I put in 2 rounds and pushed bolt release and it wont pick up round. Brass works as it should.

 

[RandallC]

Then you have some bad ammo. My ar would shoot anything but it was not a psa.

 

[Joel6180]

Lube the bottom of the bolt, and try again with two. A lot of folks will cry "under gassed", I cry "under lubed".

 

[Reconscout]

Best test is load I round and fire, if the bolt doesn't lock back you have a short stroke condition, caused but low pressure ammo, TULA being one that can cause trouble in some rifles, my 18 inch mid length gas system doesn't really like anything but 5.56, some cheap .223 works but not reliable, any AR should have no problem with steel case ammo, all of mine eat it just fine on the carbine gas system, which is basically over gassed, also check your BCG for a loose gas key, happens alot.