Quarter Circle 10 AR build

[Ten2six]

Finished my QC 10 AR 10mm a couple of weeks ago and finally got to test it out today. It did better than I expected but I still have some tinkering to do. I didn't have adequate time to test to see what loads it would cycle best. I have an 11oz. Buffer in it with an extra strength spring, it had some ftf's but I was running out of time and did not investigate further. I was having to much fun shooting the new XDM! I will report back after the next range session.

[Mike D]

Finished my QC 10 AR 10mm a couple of weeks ago and finally got to test it out today. It did better than I expected but I still have some tinkering to do. I didn't have adequate time to test to see what loads it would cycle best. I have an 11oz. Buffer in it with an extra strength spring, it had some ftf's but I was running out of time and did not investigate further. I was having to much fun shooting the new XDM! I will report back after the next range session.

10mm is finicky to get to run in an AR platform. I and running an 8" SBR with a QC10 lower and an RMW Extreme upper. I run mine exclusively suppressed but I ended up with a standard carbine spring and a 9oz buffet from Clint at heavy buffers. Runs like a champ now when suppressed. I have shot it a few times unsuppressed just to see if it would run and it wouldn't run reliably unsuppressed.





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[Ten2six]

That's a nice piece Mike D. Thanks for the info, I am going to try some loads I made this weekend. Now just have to get to the range. I've never given suppressors much thought. I might have to research that. Thanks

[Ten2six]

I ground and polished a small feed ramp being careful not to compromise the chamber support, this helped tremendously. Still not 100% though. I called Quarter Circle 10 and they emailed me a shipping label to send the bolt to them. I will update when I get it back.
Got some really nice groups so far, can't wait to shoot it again.

[Pablo]

Are you still running the extra strength spring?

[Ten2six]

Yes, the red sprinco  from qc10

[Pablo]

Thanks. Changed my RMR 10mm AR to a HD spring, might help.

[Ten2six]

If the bolt doesn't fix it I am going to call Wolff and talk to them about springs.
I also found that the magazine was a little sloppy, I could push it up tight and it would feed better. I will revisit this once I get the bolt back as well.

[Mike D]

If the bolt doesn't fix it I am going to call Wolff and talk to them about springs.
I also found that the magazine was a little sloppy, I could push it up tight and it would feed better. I will revisit this once I get the bolt back as well.

How long have you had your QC10 lower?

They had a run a while back where they opened up the magwell slightly to try to get the Korean mags to run and I cause all kinds of problems. Mine was one of those. They had me send mine in and they replaced it with a new lower using the same serial number since I had already submitted my form 1 for it. Luckily it wasn't approved and engraved yet.


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[Ten2six]

Mike D, that was their first question and mine was a recent one. I am waiting to hear what they say about the bolt assembly.
No form 1's where I live. Thanks for the input. I think the spring and buffer combo is pretty close. I just have to get a few more rounds through it.

[sad_story]

Nice build