I recently assembled an inexpensive 7.62x39 AR SBR with the following components:
Radical Firearms 10.5" nitrided barrel and gas block
Tactical Ambush bolt and enhanced firing pin
Palmetto State receiver set and parts with an H2 buffer
Yankee Hill Machine rail
CProduct Defense magazines



I've only shot ~500 rounds through it, half suppressed. Unsuppressed report was loud but not obnoxious, and trailed off with the flash hider ping. There was one hangup on the 3rd round where the hollow point tip jammed against the edge of the m4 feed ramp which was easily resolved by immediate action, with no issues since. The bolt locked back on an empty magazine consistently. The average group at 100 yards with an Eotech 512 off a bag was about 2.5"


Suppressed report was comfortably hearing safe with no ringing. The point of impact shift was unnoticeable but tightened up the grouping. 3 5 shot groups on paper at 100 yards, first two on the right sighting in unsuppressed, third center suppressed. The bolt locked back on empty too. Gas past the charging handle was a faint misty exhale.


Average velocities at 5 yards to chrono:
Tulammo 124gr HP 2150fps
Tulammo 124gr SP 2180fps
Tulammo 122gr FMJ 2240fps

Recovered from a row of waterjugs at 25 yards from chrono, 30 yards from muzzle:
Tulammo 124gr HP with pre-failed cuts  
Tulammo 124gr SP
Tulammo 124gr SP

HP's made the most spectacular impacts, but I only recovered 3 fragments from exploded jugs.The jacket split neatly along the pre-failed cuts.
SP's exploded the first jug and left its jacket, pierced the 2nd and settled in the bottom of the 3rd. The lead core mushroomed neatly.  

Wang

Meant to post this on the AR SBR

Good to hear.  I just ordered the same barrel and will be using my Specwar 7.62 on it and probably a 1-4x scope.  I'll be happy if I get results like yours.  I'm getting out of the 300BLK game and am selling my 8" barrel upper.  Just going to keep my Remington 700 AAC-SD 300BLK for accurate sub shooting and use the 7.62x39 for launching .30cal bullets on the cheap at supersonic velocities.

I came here looking for this very data. Thanks so much for the report of that stats. I am currently looking at their 7.5". Do you care to venture a guess as to how much i'll lose with 3 less inches? I could easy just go with the 10.5" but I'm really diggin that 7.5. My only concern is taking too much piss out of the round. A 7.5 inch 7.62x39 AR pistol is cute, but is it effective?

I'd like to hear some velocity numbers from a 7.5" as well.  Thought hard about getting it over 10.5".

Great post.  This is the same barrel I just ordered.  Radical has them on sale for 59.95, steal.  Also have the SpecWar 762 in jail.

Couple questions:
Did you have to adjust the gas block much?
Did you also smooth out the feed ramps?
Also, how long did it take to get that BCG from Tactical.  I have been worried to order from them?

Thanks

With the sale Radical had, I bought a 7.5" 7x39 barrel yesterday... It'l live on my FDE SBR.

Granted I also bought an 8.5 300 BO too... both barrels, gas blocks with tubes were < 160

Nice build.  Where did you find the C products mags?  They seem to be sold out everywhere right now.

I estimate 1900-2000 fps on a 7.5" barrel. The mini draco has a similar barrel length in that velocity range and gets consistent mushrooms from soft points at 30 yards, so external and terminal ballistics are fine, but internal ballistics are an unknown with a pistol length DI gas.

My gas block is non adjustable set screw secured with rocksett. The m4 feedramps are unmodified, but the edges show wear. It took almost 2 months from backorder to get the first bolt, and a week to get the second once it was in stock. It does show in stock as of today, but their web site says orders are delayed due to volume. I would buy their bolt with confidence if I needed another. Edit- Then they close up shop without a word and bolts start breaking.

I bought the newest generation CPD 30 round magazines direct from LCJ Wholesale.

double post...

C Products is now ASC.

https://www.primaryarms.com/ASC_7_62x39mm_30_Round_AR_15_Magazine_p/mgasc762-30rd-ss.htm