My AR9 build

[ssracer]

I decided on a pistol build based on a QC10 Glock small frame lower and MUR upper.
The lower was filled out with a TiN coated milspec FCG, Battle Arms Development selector, Strike Industries enhances pivot and takedown pins and a Magpul MOE SL grip.
I added a Thordsen buffer tube/cheek weld kit and installed a RRA carbine buffer and a Spike's Tactical 9mm heavy buffer.
The bolt is from New Frontier with a BCM CH, and the barrel is an 8" KAK topped off with a Kaw Valley Precision linear comp.
The front end is an SLR 8" SOLO Lite rail ceracoated armorers black by Accurate Armory to better match the flat finish of the receivers.
Attached to that via the Keymod slots are a set of G10 dragon Railscales and a Strike Industries LINK Curved Grip.
Sights are Magpul MBUS Pro.

It is an extremely fun shooter. Feeding, firing and ejecting has all been flawless with 115gr FMJ and JHP ammo. Mags used have been Glock, Magpul, and ETS. I'm going to be going through a lot more 9mm than I used to.

QC10 AR9 Pistol by Sean Dobbins, on Flickr

AR9 Pistol business end by Sean Dobbins, on Flickr

TiN coated FCG by Sean Dobbins, on Flickr

Spikes Tactical 9mm Buffer by Sean Dobbins, on Flickr

TiN Trigger by Sean Dobbins, on Flickr

QC10 and SLR by Sean Dobbins, on Flickr

Thordsen AR Pistol Cheek Rest by Sean Dobbins, on Flickr

Quarter Circle 10 AR9 Build by Sean Dobbins, on Flickr

[Gunsmokin]

Looks bad ass

[Toddstang]

Dam Sean, that is bad ass!

[ssracer]

I was just going to put a spare FCG I have in the parts bin in it but Keith threw a TiN one in it. Not for everyone, but I don't mind it.

[Robert Paulson]

better not see that thing on your shoulder. Just efile it already

[Wyldman]

I like it a lot, Sean, even the TiN coated parts. That looks wicked as hell!

I got me a rock 'n roll band - it's a free for all!

[ssracer]

better not see that thing on your shoulder. Just efile it already

I don't see any compelling reason to give the government another $200

[WLJ]

better not see that thing on your shoulder. Just efile it already

I don't see any compelling reason to give the government another $200

Not to worry, they'll figure out another way to get it out of you. After all it is their money.

[justang1997]

This looks great!

[HEYOPEY]

Looks great. Love the SLR rails

[Wyldman]

Started cutting on my lower yesterday. I've got a lot of holes to drill before I can get down to milling. This would be easier if I had a real mill, but I have to use what I have. I'll post some pics after I finish drilling and take off the cutting jigs.

Crush, kill, mangle, maim, destroy.

[ssracer]

Started cutting on my lower yesterday. I've got a lot of holes to drill before I can get down to milling. This would be easier if I had a real mill, but I have to use what I have. I'll post some pics after I finish drilling and take off the cutting jigs.

Crush, kill, mangle, maim, destroy.

good luck!

[ssracer]

Looks great. Love the SLR rails

really nice rails...and they have more length options than anyone else I have found.

[Wyldman]

Started cutting on my lower yesterday. I've got a lot of holes to drill before I can get down to milling. This would be easier if I had a real mill, but I have to use what I have. I'll post some pics after I finish drilling and take off the cutting jigs.

Crush, kill, mangle, maim, destroy.

good luck!

It's a lot easier if you use a drill press and make sure everything is square and properly measured.

Crush, kill, mangle, maim, destroy.

[guncrank1]

Started cutting on my lower yesterday. I've got a lot of holes to drill before I can get down to milling. This would be easier if I had a real mill, but I have to use what I have. I'll post some pics after I finish drilling and take off the cutting jigs.

Crush, kill, mangle, maim, destroy.

good luck!

It's a lot easier if you use a drill press and make sure everything is square and properly measured.

Crush, kill, mangle, maim, destroy.

Meh easier to buy at wholesale

[Wyldman]

Can't afford the money or the space, even at wholesale.

Crush, kill, mangle, maim, destroy.

[guncrank1]

Can't afford the money or the space, even at wholesale.

Crush, kill, mangle, maim, destroy.

Shop space got money not much here either

[ssracer]

Thanks guys. I'm loving this thing. It shoots flawlessly but I'm still working on the last round bolt hold open. Step one was trimming the bolt catch spring a little. QC10 ships a lighter spring with the lower, but it was still too much pressure. Now it will lock open on an empty mag when working the action manually, but it's still not working when shooting. I think my problem is too much mass.

The bolt is 14.6oz and the spikes buffer is 7.6oz. That's several ounces heavier than any other buffer on the market. So I'm guessing it's working the action enough to feed but not quite enough to clear the bolt catch. I've got a spacer on the way so I can use a spare carbine H buffer I have and see if that works. If it does I may try to lighten the spikes buffer. It's solid stainless so I should be able to take some weight off in a few ways.

[Gunsmokin]

Do you have a spacer in the back end of the buffer spring to limit the travel of the bolt? Heard that was something that will help reliability. Save a broken bolt catch maybe.

[ssracer]

I don't right now because I am using the spikes ST-9X buffer which is longer than a carbine buffer to compensate for that. But at 7.6oz it appears to be too heavy. I have a spacer coming so I can try a carbine H buffer. I've been in contact with qc10 and they said they recommend about 5.5oz for buffer weight.

[Wyldman]

Do you have a spacer in the back end of the buffer spring to limit the travel of the bolt? Heard that was something that will help reliability. Save a broken bolt catch maybe.

I got one for mine. The buffer I got was designed specifically for 9mm AR pistols, and this damned thing weighs a ton!

Crush, kill, mangle, maim, destroy.

[Gunsmokin]

I don't right now because I am using the spikes ST-9X buffer which is longer than a carbine buffer to compensate for that. But at 7.6oz it appears to be too heavy. I have a spacer coming so I can try a carbine H buffer. I've been in contact with qc10 and they said they recommend about 5.5oz for buffer weight.

Do you have a spacer in the back end of the buffer spring to limit the travel of the bolt? Heard that was something that will help reliability. Save a broken bolt catch maybe.

I got one for mine. The buffer I got was designed specifically for 9mm AR pistols, and this damned thing weighs a ton!

Crush, kill, mangle, maim, destroy.

Sounds like a spacer for the back of mine will also be on order soon. I have an h3 buffer. Hoping it will function with it.

[Wyldman]

I haven't been able to do much more than dry fit parts up to now. I'm still working on the 80% lower, taking my time and trying to do it right. It's a little nerve wracking until I get the cutting done. This the first one I've attempted, and I can't afford an expensive paper weight, as was observed not too long ago by one of our brethren here.

Crush, kill, mangle, maim, destroy.

[Gunsmokin]

I don't have the patience to mess with an 80% anything.

[Wyldman]

I do, I like working with my hands and chunks of unyielding metal can be rewarding (& cheaper!), but it takes careful attention to detail and a lot of patience. As the old saying goes: you can always take more off, but you can't put it back on.

Crush, kill, mangle, maim, destroy.