u/Much_Bar_7707

Hi new to this thread but longer time AR22 fan. Built my first 16” probably 5 years ago. Recently wanted a shorter 22lr pistol/pdw and couldn’t find a 10/22 Charger, so did built a short upper to toss on a folding stock pistol lower I have. Build is a 7” (or maybe 8”) CMMG barrel, CMMG bolt from a conversion kit with a RTB collar, and a Bore Buddy bolt buffer. Took to the range with some standard velocity ammo (probably Federal RN lead 40 gr) in Black Dog 25 rd magazines. It worked better than expected (one ftfire in one magazine.)

Also got a new can…it’s a 9mm can, but I was going to see how quiet with 22lr subs as seriously considering getting a 22 can. Things went wrong there. Using CCI quiet ammo I couldn’t get 90% of a box of 50 to feed. When I did get a round chambered and fired it would short stroke and not cock back the hammer. This is 20 minutes after it worked perfectly.

Advice/parts to make this run reliably? Is this just an issue with the ammo? Will standard velocity 22lr ammo drop velocity to subsonic in a 7” barrel (vs 16)? Assume it was the ammo but advice on what to and not use? Spring change suggestions?

EPC 9 11" Pistol Build

Lots of very lightly used parts on this picked up from my local FA community

Aero EPC upper and lower. Personally prefer FM lower LRBHO but this started out as an idea of putting the upper on a rifle lower with a conversion block and I needed an upper that had LRBHO. I saw this receiver builder set on deep sale and this came out of it. New parts
BA EPC Modern 11" barrel. New part.
BKings 9mm bolt. New: thanks to BB9 for the suggestion/source.
BCM 10" MCMR handguard-- This would be overkill and cost prohibitive if purchased new, but for $100 used...yes please.
Used BCM Type III grip - parts box
Sig Romeo - parts box.
Troy BUIS purchased on sale during some black Friday holiday sale...probably also overkill for an AR9, but they're nice.
Law Folder - Used for about $90
BCM large asymmetrical charging handle - parts box
Turn-Key GRS (gentle blowback system from Blowback 9's testing) with the long JRC buffer tube, Kynshot hydraulic buffer and tungsten weights, bought off some guy used--he was buying an internally sprung AR Upper--and I came across his classified as I was pricing out the parts...
Flat wire spring - parts box...I think it was Strike or Wilson Combat...
Aero mil-spec parts kit -parts box but maybe supplemented.
SBA 3 brace - used for $40, but I think it might be a knock off because the QD socket on the brace doesn't work. YGWYPF
CMC Blemished PCC trigger pretty deeply discounted. I used to have a GS2 trigger in it and that worked fine but that's been moved to a rifle caliber AR
Standard magpul sling, clips, mlok QD sockets, etc.
The Obsidian 9 is new to me and new. Haven't shot it with this yet. Just barely fits on the barrel with this handguard.

Super reliable with OEM Glock, ETS and Magpul magazines. Pretty accurate too...at least for me.

Thoughts: 11" makes some sense to maximize ballistic performance, but 8" seems to make more sense if I'm going to suppress this because it's longer than a 16" carbine at this point. Honestly between the 11" barrel, the heavy bolt and buffer system AND the law folder this thing weighs a bit more than one would imagine. I think it's approaching 9lbs without suppressor; in fact the suppressor makes it feel a bit more balanced. I'm happy to sacrifice 3/4 lb to reliability with the GRS buffer weights and bolt weight, and ability to fold is also pretty great and worth some weight. I think the only thing I can do to get the weight down is to swap out the 11" straight barrel for a pencil 8" barrel with shorter and perhaps lighter hand guard with an aluminum barrel nut.

Suppressor and Subsonic Feed and Short Stroke issues.