Test-firing a Suppressed SBR 9mm AR (video)

[OEF_VET]

I recently built a suppressed, short-barreled 9mm AR for a customer. The gentleman who purchased the rifle is a Blackwater operator, somewhere overseas.

Today, we took the rifle out for its first test-fire.

We ran into some problems trying to run 147gr JHP's at first (Golden Sabers and Hydra-Shoks). We added some lubricant, but that didn't seem to eliminate the problem.

Switched to 115gr CCI Blazers, and still had a few problems at first, with rounds failing to feed. I believe the failures were primarily related to the inexpensive USA-MAG brand magazines we used. Unfortunately, Colt original 9mm AR mags run about $60 each. I guess I'll have to locate a couple to toss in with the rifle, as it doesn't seem to like the cheap, plastic ones.

Video is attached:
(Keep in mind, the ammo is supersonic, and the rifle is being fired indoors, which is why it seems so loud.)
9mm SBR test-fire video

 

[Mtdew]

FTFeed or FTE? i cant tell from the vid

Try uzi mags. No BHO but they work very well for me. There are some dim's on the hahn site as to where to cut the mag catch slot

I assume you were using pro-mags (as im not aware of another US plastic 9mm ar mag) they are hit and miss as far as I can tell. Some people swear by them.. and some have the same issues you describe. Also check the ejector for play(RRA espically) also make sure the ejector's high enough to allmost contact the bottom of the ejector slot in the bolt

another question is what is the setup?

whose mag block? RRA, Colt, Hahn
whose upper?
barrel length?
supressor (integral or detachable) if detachable (QD or threaded)
ramped or standard bolt

*edit*
ok i just watched the vid again it looks like FTE.. Definitely check the ejector for the correct height and looseness. also check the extractor pin and make sure it's a roll pin and not one thet looks like a rolled up newspaper(RRA bolts had issues w/ those)

 

[OEF_VET]

MtDew,

Yes, the mags are Pro-Mag. The problems were mostly Failure-To-Feeds. The JHP's were especially bad. I did have one FTE, which you can see in the video, with the case sticking out of the ejection port.

The rifle consists of:
DoubleStar lower
VLTOR Carbine stock
DPMS hammer (to go back-and-forth between 9 and 5.56)
9mm buffer
Hahn bottom-loading mag block
DoubleStar 9mm A3 upper
TROS 5" 9mm barrel
PRi Carbon-Fiber Free-Float handguards
PRi GasBuster charging handle (works REALLY well - no blowback at all)
PRi flip-up front sight
ARMS #40L rear BUIS
ETS thread-on 9mm suppressor