What parts work best with them and what build advice do you guys have?
I'm hoping to file form 1 on this thing as soon as I get it.

Tagged.  This is relevant to my interests.

Yep. Boatloads of good info inbound to this post.  
Any day now

Mine uses a side charging upper from New Frontier Armory and CMMG bolt.

I like it except for that cavernous ejection port.
How's it run?  Did you have to do any fine tuning like changing parts or dremeling stuff to make it run?

No problems, essentially it was plug and play, no dremel needed.

That's excellent!  I'm kind of intrigued by a side charging upper.  

Another nice thing about the QC10 lowers is the proprietary parts are already installed. The rest of the build went like your run of the mill ar.

Its also fun supressed too

what buffer and trigger are you running?
I keep hearing that a lot of the better triggers like Geissele triggers won't work with the 9mm bolts.

I am using the colt 9mm buffer that you can buy from Brownells or Midway.

The trigger is the ALG Advanced Combat Trigger.

I will try to give a run down of my setup.

I have a QC10 CLT lower, QC10 MUR upper (small ejection port) and also a QC10 barrel. I ended up running a "blem" 9mm ramped bolt from PSA ($49 FTW). Most of the other parts aren't going to make it run smoothly so we can talk about them later. I wanted a gun with a barrel long enough I could still get my support hand farther forward than  most with these 5.5" barrels.

My buffer ended up just under 9oz and it uses a Wolf XP spring. It will run on any 9mm ammo you want. I had heard that the QC10 barrels worked better with the lowers. I doubt it, but I bought one anyways when I bought the upper receiver.

I have ASC magazines and they run flawless. I have not had a FTF/FTE with these mags. Mine is a very fun gun to shoot and is smooth as can be. Easily my favorite gun to shoot that I own.

I do not have any pictures of it as I am on my work computer and it is firewalled :/

QuarterCircle10 colt lower, Vltor upper (no forward Assist), Kaw Valley Precision 8.5 barrel, JP Bolt with JP silent capture buffer system (9MM).  Rail is 8" SLI Rifleworks. The trigger is Hyperfire 24c. Love it very fast firing !

Magazines are a mix of 32 round Metalform, ASC and 1 20 round.

That's sounds like a cool setup!
How's it run?  Is the jp silent capturer buffer system worth the money?

Picture of said weapon since I'm not at work anymore




It's my favorite blaster

Had a few issues on my build, #1 screwup on my part was not checking for the firing pin spring ! That led to myself and few others thinking all sorts of possible causes when it turned out it was a missing spring.  My first trigger Wilson Combat TTU also worked only so so. Once I added spring and the Hyperfire 24c trigger the gun came to life big time.  Most fun factor gun I own easy. Super super fast firing and I love the Shockwave "brace". Looks good and cheaper than the Sig.

The JP bolt/capture system is also very nice. You do not hear that spring twang, in fact I do not hear anything so yea love it and will be switching my AR's to the silent system.

Make sure you stock up on mags and a mag loader. I have three different brands and the Metalform and Brownells work best. My 20 round mag C Products ? (Has orange follower) is not as reliable. Brownells has a sale for three 32 round mags also. I was unable to locate any in stock Metalforms.

When I get a chance I will post a pic.

Good luck