Ar won't run steel cased ammo

[BIBM502]

I traded into an AR that appears to have a fairly low round count. Aero upper and lower, vltor buffer tube kit and Midwest industries bcg. It will run brass all day long without issue. If I load a mag of steel cased ammo it will not run two rounds in a row. Majority of the failures are FTFeed but there is the occasional FTE. The Midwest Industries bcg is spotless and in great shape, borderline looks new. I've disassembled, cleaned abd lubed it with no change in performance.
The reason I know it is the bcg is because I swapped in a triarc bcg and had zero malfunctions.
Any ideas would be greatly appreciated. I'd hate to have to replace the MI bcg if it's a simple fix.

 

[KOMRAD]

See if you can localize the issue between the bolt or bolt carrier by swapping the MI bolt into your Triarc bolt carrier.
Also Ive heard of issues with Vltor buffer tube kit having issues with pistol length barrels/gas length/dwell time (if this applies to your AR).

 

[Sowega86]

If it's Wolf ammo the primers may be too hard for the firing pin. I had to replace the firing pin on a US-made AK because it had difficulty punching a dimple onto the primer.

 

[BIBM502]

See if you can localize the issue between the bolt or bolt carrier by swapping the MI bolt into your Triarc bolt carrier.
Also Ive heard of issues with Vltor buffer tube kit having issues with pistol length barrels/gas length/dwell time (if this applies to your AR).

I'll try swapping bolts/ carriers next time I hit the range. It has a 14.5" barrel with a keymo muzzle brake p&w.

 

[BIBM502]

If it's Wolf ammo the primers may be too hard for the firing pin. I had to replace the firing pin on a US-made AK because it had difficulty punching a dimple onto the primer.

I was running tula. It didn't have any issues firing the round once it was chambered. Main is failure to feed.

 

[cmshoot]

When you say “FTF”, are you saying “failure to feed”, or “failure to fire”?

Vltor makes standard carbine receiver extensions and their A5 RE’s. Which are you using?

 

[cmshoot]

We were typing those at the same time!

 

[BIBM502]

When you say “FTF”, are you saying “failure to feed”, or “failure to fire”?

Vltor makes standard carbine receiver extensions and their A5 RE’s. Which are you using?

My apologies, failure to feed.
It has a five-positon RE-1 Mil-Spec Carbine tube

 

[cmshoot]

When you fire the last round of Tula, does the bolt lock back on the empty mag?

 

[BIBM502]

When you fire the last round of Tula, does the bolt lock back on the empty mag?

I couldn't tell you because I wasn't able to get through a full mag without frustration so I never made it there.
Should have fired it with just a single round in there to see.
Will put it on the list of things to test.
Edit*
It did lock back with the triarc bcg though.