Ok one of these (at least) will happen this week. I haven't fired any of these so I need some help. This will be suppressed and unsuppressed if it matters. Mainly just a fun gun.

1) 9mm mag block. Can use existing SBR lowers.
2) Dedicated Colt lower
3) Dedicated Glock lower. Mags compatible with pistol.
4) CZ Scorpion Evo

Thanks

I built mine for potential use in USPSA Pistol Caliber Carbine , with reloads off my pistol belt.... I shoot a G34, so the Glock choice was fairly obvious....I don't need last round bolt hold open... my 16" complete NFA lower and bolt, with Aero Precision upper and barrel from MAS defense with RRA NM trigger was a little under $900

If money isn't a big concern, get a dedicated lower.  Much better looking, IMO.  The Colt lowers have consistent last round bolt hold open (and I think the straight drop on the mag looks better personally), the Glock lowers are much trickier.  I bought the Brownells Colt 9mm Mags, they look and work great and hold 32 rounds for $35.

I like the dedicated Colt myself. Hopefully Spikes will get theirs out before it's to late. If not may have to get either a PSA or BCP.

All four.

Its AR15.com after all.

If you sbr, mag block will let you swap uppers to switch to 5.56, or whatever upper/caliber you like (dedicated lowers won't)

QC10 dedicated colt lower. Love mine, excellent fit, finish and true bolt hold open.

I like the Black Creek Precision EF9 dedicated Colt Lower I just got.  A few of the nice features it has are a threaded pin instead of a roll pin for the bolt catch, a small block that transfers the lift from the magazine follower so it uses a standard AR bolt catch and a threaded hole for the rear take down pin detent.  Plus I like the classic look of a forged lower receiver.  I only have a couple hundred rounds through it but it seems to play well with the RRA upper and bolt I'm using.

Glad to hear that... I just received mine yesterday and am going to submit the Form 1 this weekend.

I think I've narrowed it down to either a Colt or Glock dedicated lower. I'm local to Black Creek Precision and I have talked to them. I'm leaning heavily towards the NFA Glock lower with a JP SCS and bolt with a 4-5" barrel and pistol tube until I SBR it.

i have both a Black Creek dedicated lower and another running a hahn conversion block. If I had to do it all over, I would go with the dedicated lower and spend my money on extra mags....I prefer the colt platform to the Glock platform.

Either way these PCC are lots of fun to shoot.

I just bought a Thor's Hammer Glock Lower from Runner Runner Guns and it is easily one of the best lowers I have owned for fit and finish and overall quality.  

Recommend them highly

I picked up a pair of CAR-16/9mm Colt complete upper assy back in the early 90's.  They sat on the shelf for years until I bought a CMMG Colt pattern dedicated 9mm lower. I put a early M16 butt stock and used the std rifle buffer. A DPMS rounded hammer (not notched) LPK finished up the build. Bolt is still factory (not ramped). Everything runs great with any ammo I choose to feed it. I'm using the Metalform mags sold by Brownells and some actual Colt branded mags.

Recently I ordered up a PSA dedicated Colt pattern lower to build up with that barrel assy #2 that's still collecting dust. Have not had time to stop by my local Gun dealer to pick it up yet. Will be interesting to try them side by side. As is the CMMG runs perfectly as long as the shooter does his part. Failing to insert the mag enough to engage the mag latch will have the normal predictable results.

You can either go with a QC10 Glock lower of a CMMG Mk9 lower.



QC10 Glock 9mm lower, with modified bolt to work with Glock magazines.




CMMG Mk9 Lower; the magwell is purpose-milled for 9mm magazines and it includes everything, from the extractor and ejector to the bolt catch.

I originally started with an Anderson lower and psa 9mm mag block. After getting everything then noticing the it was really hard to charge and was having like mag fit issues I went and got a Spartan 9 glock lower aka Joe Bob lower. I couldnt be happier! Paired with my side charger it's awesome.

The qc10 I think is over priced and the Spartan does a great job at half the price

I think a dedicated lower is the best option. Take it from a guy that was going the spare lower + mag block route. You will have less problems in the end. The QC10 glock lower looks nice but I think my Spartan 9 lower does it all for half the price.

The bolt catch pin is threaded. The safety pin dentent is also threaded.
And the mag release design is like most glock lower types.

Spartan 9 glock lower
Spinta precision glock bolt blem(best Damn deal ever!)
Matrix side charge upper 9mm
Shockwave Blade
4 inch kak barrel
Guntec keymod
Kak 9mm flash can
Pof USA Drop in Trigger 4.5lb
Spikes heavy buffer

This setup is freaking beautiful. I only wish I got into AR 9mm before I filed to sbr my 7.5inch AR. The only reason I'm not filing for SBR on this ar9 is because I have an mpx that's sbr. so that's why. If I had bought an mpx before the whole ar9 I wouldn't have built this one. But I gotta admit. This thing is pretty fuckin awesome. I'm really only spending money on my mpx but I think this still needs a few accessories like a grip.. Sights.. Etc