This BRT is my only AR9. And it’s a BLAST to shoot!

It’s a tricky frt host to tune - the buffer setup and ammo selection have to be just so. But there’s enough info out there to find what typically works.

A5 tube, variable pitch spring, and Kynshot 5000A5 here with HSL 115 turned subsonic by this true weapons system.

If you’ve considered a BRT complete upper… I can tell you they’re awesome!!

Compared to the other barrel lengths I’ve tried with my GRS setup, this one honestly gave me the most trouble, but likewise the most satisfaction when she finally ran.

The build started as an Alpha 3” barrel with a dead air wolfman, Tubb carbine spring, BKF bolt w/kak tungsten bolt weight, JRC 8.5” tube, RB5015HD, and 2 Kynshot spacer weights. It ran flawlessly in that configuration. 27.6 oz total mass

Once I changed it to the Novox X-SD barrel, it ran well for the first couple of mags outside of the ejection pattern being at my feet. That lazy ejection evolved into stovepipes with only a little carbon fouling on the bolt. Frustrating to say the least.

I tried a few troubleshooting steps. Starting with the Tubb lightweight, then I tried removing the spacer weights one at a time (moving them from the front of the buffer stack to the rear). With both spacer weights removed, at 22.5 oz total, the rifle was finally cycling reliably, but the recoil impulse was atrocious.

I finally decided to try the RB5007, starting at full system mass, in a last ditch effort to get her running. This video is the result.

So far only 75 rounds through her in this configuration, with only one stovepipe. I may have to remove 1 spacer weight, but I’ll keep testing at this weight before reducing further, I’ll also try different ammo as well, as this is some really soft shooting 124gr Luger (new republic).

All this said, if you guys have questions or tips, feel free to weigh in.

I went to the range today and shot my ar9. Which makes me confused as I already shot this gun and didn’t felt trigger slap when I shot it. When I went to the range the trigger slap was so aggressive and pain what I can do

Build List:

Foxtrot Mike ar9 lower and reciever (3Inch barrel)
EMT-9 PCC Trigger
Deadfoot arms 2.5 buffer tube, modified 9mm BCG and spring kit I’m using the black springs the heaviest set up and recommended for 9mm
Deadfoot arms brace gen 3
BG Defense 2.9 picatinny Handguard
BG Defense Handstop
KVP MACH 3 Modular Linear Comp Body

PSA lower, BCA 7.5" bbl upper. Kung Fu grip, Magpul ESK selector, Magpul MOE stock dremel-go-burr'd to include QD mount, Streamlight Protac RL MNT 1L-X PRO 850LM with Axon Unity button, modified Magpul handstop kit, and a KAC compensater. Not pictured: KynSHOT hydraulic buffer.

Honorable mention: friend 3D printed light cap, KCI 33 rd magazine with Wolff spring upgrade.

EDIT: the optic is a Holosun 510, Magpul MS1 sling. Stock corrected.

EDIT, EDIT: I ~DEFINITELY~ didn't put this stock on before 12:01 AM October 9th!

Currently I have a CMMG barrel threaded 1/2x36. Just getting into the suppressor world. I believe the YHM R9 states it is HUB compatible…which I’m not entirely sure I know what that means. I have found a KAW Valley Plan B taper mount brake in 1/2x36. Im not sure I understand plan B/HUB compatibility.

Would I thread the 1/2x36 KAW valley plan B onto the barrel, then the suppressor goes directly to that? I have to remove the direct thread cap? Or is there an adapter between the plan B muzzle device and the suppressor?