Quarter Circle 10 AR40

[Sniper338]

Anyone got any experience with quarter circle 10 AR style carbines? Ive been looking at pistol caliber carbine rifles for a while now and quarter circle 10 seems to be of the best quality from what I can find. Even matches my wanting to utilize glock magazines.

Looked at:
Just right carbines
Ruger
Beretta storm
Cmmg
Everything else factory carbine wise..

QC10 seems to be the best on the market.. also the most expensive, but id rather have the quality and functionality that Im looking for.

Any reviews?

 

[PhilKeil]

I have one I built into a 9mm. It runs great no problems really love it. I also have a 45 ar 15 with grease gun mags. been thinking of getting another Glock mag lower and swap it out as I have a Glock in 45 and could use the same mags. I really enjoy the pistol caliber ar's the most. we also built a 45 win mag ar 15, and 2 - 9mm win mag wild cats. All are DI not blow back. Only down side is the DI gas system is, the potential to clog if you run lead. I have not tried it with lead bullets so I dont have 1st hand knowledge of that but a good friend has a m16 and had a 22 conversion and if he ran a bunch of 22's when he went back to 223 he had a bunch of malfunctions until it cleaned out the gas system. If you have questions I am happy to help. Ps I think 1 of the other forum members has shot them all if you need further info.

 

[Sniper338]

I have one I built into a 9mm. It runs great no problems really love it. I also have a 45 ar 15 with grease gun mags. been thinking of getting another Glock mag lower and swap it out as I have a Glock in 45 and could use the same mags. I really enjoy the pistol caliber ar's the most. we also built a 45 win mag ar 15, and 2 - 9mm win mag wild cats. All are DI not blow back. Only down side is the DI gas system is, the potential to clog if you run lead. I have not tried it with lead bullets so I dont have 1st hand knowledge of that but a good friend has a m16 and had a 22 conversion and if he ran a bunch of 22's when he went back to 223 he had a bunch of malfunctions until it cleaned out the gas system. If you have questions I am happy to help. Ps I think 1 of the other forum members has shot them all if you need further info.

Good to know they run good. How "accurate" ate their barrels? Pattern pretty good? I mean a handgun can run a ragged hole, im curious what one of these will do in a 16inch barrel...

 

[Cecil S.]

Hmmmm.....10mm AR very cool.

 

[PhilKeil]

My 9mm has a 16 inches long tube and shoots real well. I cant remember group size but i was not embarrassed or wanted to get rid of it. I can shoot it this weekend and shoot you a pic of the target if you like. I put a red dot on it. On the 45 it is 14 in long with a 2 inch thread adapter for my can so to keep it legal. It shoots real well also . at 50 about 1.5-2 inches and very quiet. I have no problem with bowling pins at 50 yds I have used it to dispatch some vermin. I have put the can on the 9 but it has a little crack unless i use the 147's. But to be truthful i did not spend a lot of time working up any loads for either one. I just use what i have loaded for my glocks. Btw funny thing is on the 9 it picks up velocity over the glock a lot more. My 45 win mag is about 1 inch at 100 and claimed a couple of deer with neck shots, 1 at 110 yds and 1 at 120 yds. Those we are pushing hard, faster than 450 bushmaster factory.

A couple more I had thought about was 10mm mag and 357 sig. Either 1 leaves a lot on the table in a handgun but i bet in the rifle would be great. Not to mention you could do it in a glock mag ar as well.

 

[PhilKeil]

Ps
I have seen video of a 50 gi that was kinda cool

 

[USMCDOC]

My 9mm has a 16 inches long tube and shoots real well. I cant remember group size but i was not embarrassed or wanted to get rid of it. I can shoot it this weekend and shoot you a pic of the target if you like. I put a red dot on it. On the 45 it is 14 in long with a 2 inch thread adapter for my can so to keep it legal. It shoots real well also . at 50 about 1.5-2 inches and very quiet. I have no problem with bowling pins at 50 yds I have used it to dispatch some vermin. I have put the can on the 9 but it has a little crack unless i use the 147's. But to be truthful i did not spend a lot of time working up any loads for either one. I just use what i have loaded for my glocks. Btw funny thing is on the 9 it picks up velocity over the glock a lot more. My 45 win mag is about 1 inch at 100 and claimed a couple of deer with neck shots, 1 at 110 yds and 1 at 120 yds. Those we are pushing hard, faster than 450 bushmaster factory.

A couple more I had thought about was 10mm mag and 357 sig. Either 1 leaves a lot on the table in a handgun but i bet in the rifle would be great. Not to mention you could do it in a glock mag ar as well.

i have a Palmetto AR9 that just hammers.. loves Herters 9mm

 

[Sniper338]

Ps
I have seen video of a 50 gi that was kinda cool

Ive been real curious what a 357 sig would do in a 16 inch barrel. Its a power punch in my glock. I just have a boat load of 40 cal loaded up. So ill do a 40 first... eventually, when finances allow me to again. (Remodeling a house currently)...

 

[USMCDOC]

Ive been real curious what a 357 sig would do in a 16 inch barrel. Its a power punch in my glock. I just have a boat load of 40 cal loaded up. So ill do a 40 first... eventually, when finances allow me to again. (Remodeling a house currently)...

your biggest hurdle will be getting it to feed reliably.. out side that, should be a real neat project

 

[PhilKeil]

The glock mag I feel makes it easy. As I understand when they started designing the lowers there was a school of thought that moved the mag closer to the barrel. Please remember all this started with grease gun mags and 45 acp. The mag to close caused feeding issues. Someone relocated the well rearward and it straightened it out. When glock mag stuff came out I feel it made it easier. Most all pistol AR were designed as blow back. Because of that changes have to be made example springs, heavy buffers, solve ejection problems. If you go DI all the internal workings are the same as a regular AR and interchangeable and all you have figure out is where the gas port needs to be placed. Example on my 45acp one it is real close to the chamber about 2 inches in front. on the 9 i will have to look again, on the 45 win mag it is standard carbine. If you really want to get into the smithing part i can explain the process in how to calculate where the gas port need to go . It is not hard. Also you do have to open up the bolts for the rim of the case.
I did have 1 problem with the 9mm. I had some ammo that was loaded with fed primers. well they are soft and well lets say the mass of the firing pin moving forward would set them off. it would empty a mag very fast. needless to say i dont use the fed primers anymore for it and for safety sake i changed the firing pin to titanium and problem fixed.
Holler if I can help

 

[Bamban]

PK,

I have some questions.

Interested in doing a pistol caliber AR, do these QC 10 systems take standard AR barrel extensions?

With your experience, which is your preference, the DI or blowback? Why?

Would you kind enough to share gas port size and location calculation on the forum or through private messaging/email only?

Thanks,
Nez

 

[Knotwild]

I went cheap because I just have it for fun. It's a PSA that I bought as a complete upper and a complete lower. I am not a fan of the 300 BO and I preferred to go with a .45 acp because I could build it as a pistol and send a 230 gr bullet out subsonic.

 

[PhilKeil]

PK,

I have some questions.

Interested in doing a pistol caliber AR, do these QC 10 systems take standard AR barrel extensions?

With your experience, which is your preference, the DI or blowback? Why?

Would you kind enough to share gas port size and location calculation on the forum or through private messaging/email only?

Thanks,
Nez

Nez,
Pleasure to meet you. I know your close to Austin and I am in San Antonio. If you would like to see them in person let me know and we can meet up. We may have meet a few yrs ago as as a kid a neighbor would get us kids to pull targets at bullis. He was big into the high power shooting. My neighbor taught me a lot and wish i knew more.
I favor the DI as it is cleaner, no special parts. feed and ejection is all consistent with conventional ar 15 systems we know. No special buffers/springs etc. I know you have a lathe so opening the bolt is no big deal.
Yes use the same extensions for the smaller calibers. for larger calibers they make a larger feed ramp version like for the 450 bushmaster. Using that one would save some time but it can be done with the standard one. for the 9mm i had to do nothing. for the 2 wildcats that are feeding from standard ar mags i had to open up the ramps a little and polish it some. I may have 10 min in that part.
To figure the gas location I was taught to use Quick load and make calculations based on the point where the chamber pressure drops below 10,000 psi. In QL when you set up you will see a chart. if you hover the cursor you can get chamber pressure in relation to barrel axis. please keep in mind you have existing gas tube lengths to use so you have to be close as possible to the parts you can buy. example from a wildcat i built


at about 6 inches it drops below 10,000 so i used a carbine gas tube that is about 7.5 in long. For port size I got lazy on the last 3 and used adjustable gas blocks and drilled the hole the same size as the hole in the block and just fine tune it at the range. I think this is the easiest way.
Back on the gas tube for 45acp the tube has to be cut down real short . The port is about 2 inches in front of the chamber. but this leads me to when i first stated with the 45 i was pushing it real hard and over gassing. once i brought it back down to normal levels it was fine.
I am sure I did not answer all the questions please ask away.
phil

 

[Bamban]

Phil,

Yes, I am in Austin and quite sure we met at Bullis when we used to shoot there back in the 90s. In fact, I shot at twice a month there with my service rifle, the across the course club match and the Palma course.

I would love to meet in SATX with you to check out your pistol caliber ARs. Most likely I will stick with the 9MM or maybe the 357 SIG. My G22 and 34 have been converted to the 357 SIG. On another note I just finished a 5.45x39 upper since I have a few spam cans of that Russian army ammo. Got the 17 inch blank from Green Mountain for 37 bucks.

How convenient to use QL, and I am very familiar with it, have used it since it was introduced. I never thought about extending its use for this application.

Here is my contact information.

bambanbarrelbarn@gmail.com


nez

 

[ToddKS]

You might look at the ATI Milsport in 9mm. I have one and it has never had any issues. Using a good factory Glock mag is key. The only feature it does not have is last round bolt hold open. I changed out the grip and buttstock on mine and was in it for less than $750.