Home Forums Hunting & Shooting AR and Tactical Rifles Build a 9 on Mil-spec lower? Barrel length? Magwell?

Arms overflowing, however, missing a PCC suppressor host car rig. Ruger PC9 was was too f'ing long with 16" barrel. So, going "pistol".

Thinking 9-11" for velocity. Matters? Wait, I think 8" is the ticket. That's what she said.

A PSA complete upper wound be a cinch.

Magwell, magazines? Glock19 compatible would be handy.

Or, skip the mil-spec AR lower all together? Buy full rig? PCC specific lower? Just use a 556, lol?

No, just 9mm, not 10mm or 45ACP this time.

Side-folder on this?

Yes, it'll have a light! And a sling. No BRC. Sheesh.

Half-intelligent input? Comments? Considerations?

Like this would satisfy I think.



Yah. Purpose-built 9mm lower looks like the way to go.

Just finished a 9mm on an Aero receiver set. Dedicated glock mag lower, and the Aero upper has a kinda cheesy looking last round bolt hold open that seems to function fine. 11 inch barrel, m-lok guard, flip up sights, and a Crimson trace light / laser, the one that has the switch in the grip.
Might end up SBR'ing it just because.
Put a couple mags of mixed up ball / various hollow points thru it yesterday afternoon, no failures of any kind.
Not nearly as loud as a short 5.56, and 'should' be fine as a truck/ around the farm/ inside the house rig..

Thanks for the input.

Looking more at the FM9 Glock mag lowers now and thinking 7 or 8"... Hmmm. I have all the lower parts needed, I think, so $160 plus an upper would get things going.

Ordered a threaded Glock 19 barrel as an aside.

Gone with an 8.3" Ballistics Advantage barrel, Aero EPC lower, and a Toolcraft BCG. The rest to be scrounged from what's on hand, to see how, and if, it goes.

FWIW
Some 9mm velocity/barrel length discussion.

https://www.80-lower.com/80-lower-blog/the-ultimate-ar9-pistol-guide/

Just a heads up, but the last round hold open on the EPC lower only works within Aero EPC upper.

Yep, thanks again. That'll be on the list of potential upgrades. For now, I have a slickside 556 upper to use.

Hmmmm... Everything in 'cept the higher capacity mags.

Hopefully it'll run. 5.7oz buffer and a heavy blue spring. Used $1.50 for a spacer. FIIK.

Suggest you make sure you have the heaviest buffer you can find to cancel out bolt bounce. I started out with 4.3 ounces and had OOB fires. Went to 7.6 and have no OOB's yet, but still seeing slightly swelled cases. Anything over 8 ounces should do it. Dedicated lower to take Glock mags and grab a 50 round MagPul drum when they come out. The Pro Mag 50 round drum works fine too for half the money.

Ran like a raped ape for 45 rounds, albeit fairly harsh. Have ordered an AR9 specific buffer and 308 spring to mellow it a bit. Real pleased with the 8" barrel choice. IDK if the lack of lrbho is going to bother me on this. Fuggin ammo prices.

The heavy buffer will help out a lot with the harsh recoil and help keep it from beating itself to pieces. I think my 9mm buffer is 8 ounces.
For mags, Classic Firearms , and I'm sure others, have a Korean made, not sure of the brand, "SBM" maybe?, I'll have to pull one and see, of glock mags, that run great, drop free and act just like OEM mags. About 15 bucks for the 33 rounders.

9 mm AR bolt carrier group plus buffer 22.5oz +/- 1oz is a good way to be at with the use of a standard buffer spring. Prevents violent extractions bolt bounce and if one wanted to can run with certain real fast triggers and lessen the risk of firing out of battery.

Hmmm, fun. Ran " real good" suppressed at 21.8 oz with the recommended (for this buffer, Aero EPC 7.7oz) 308 spring. Used 124gr FMJ standard pressure loads, Czech STV Scorpio. Swapped a more vertical grip, joy.

Besides, "Hey, it works" what might I look for before calling this thing GTG?