Quarter Circle 10 Side Charging Uppers

Quarter Circle 10 debuted their aluminum AR lowers that accept Glock mags last year, they now have a non-reciprocating side charging upper on the way. It works with any of Quarter Circle 10’s blow back bolt assemblies (sold separately) and also works with their 9mm, .40S&W, .357 Sig and .45ACP barrels (also sold separately). The Quarter Circle 10 Side Charging Uppers are currently on pre-order and pricing is still TBD, check out quartercircle10.com for more info.

Our upper features a non-reciprocating charging handle. This allows the operator to remain in the firing position while charging the firearm. You can easily pull the charging handle to the rear and active the bolt catch with one hand in one motion. This upper was designed around mil-spec standard and will accept any of our blow back bolt assemblies. This upper has an enlarged ejection port and will fire pistol calibers from 9mm to .45 ACP. Our upper has a trap door in the rear to keep dirt out of the upper and allow easy removal of the bolt from the receiver.

Ray I.

Long time gun enthusiast, archery noob, Mazda fan, Sci-Fi nerd, Whiskey drinker, online marketer and blogger. My daily firearms musings can be found over at my gun blog ArmoryBlog.com and Instagram.

Shoot me an email at ray.i@staff.thefirearmblog.com


  • Vhyrus

    If only the makers of the Tec-9 could see how far we’ve come.

    What? They’re still alive? Are you sure?

  • ozzallos .

    Website says their small frame model (pictured) only takes 9/357/40. The large frame version will take .45 and 10mm(!) glock mags. But…. a buffer tube? Any of those would be amazingly viable with a folding stock, or no stock at all.

    • CTFish

      Then you’d have a pistol that takes glock mags

      • iksnilol

        Or, you’d have a really handy PCC?

        I mean, 3 inch barrel, folding stock, aimpoint, 9.5 gram bullets and you’d have a really handy 100-150 meter gun.

        • You’re describing a Glock SBR, which you can create with any number of chassis systems. I have one, and while they’re not cheap, they are damned handy.

          • iksnilol

            Eh, I am a bit sceptical of the pistol SBR kits. All I have seen have had some problems with ejection. + they look so bulky.

            Though they are probably practical.

          • I think the current Internet wisdom is that semi-compact Glocks (eg, the 19) don’t work well with a chassis (in terms of ejection issues). My Glock 17 setup is boringly reliable, for comparison.

          • iksnilol

            I did not know that.

          • Yeah, take a look at Short Barrel Shepherd’s experiences with a G19 and the various stuff he tried… seems like the common thread. This entire discussion is reminding me that I need to tweak my KPOS setup to tighten up the vertical play.

      • Panzercat

        Except for the folding stock part.

  • mig1nc

    Shouldn’t “quarter circle 10” be “arc 2.5”? LOL. OK. That was a horrible joke.

    But on a serious note, I wish CMMG had done this with their mutant. I like how they implemented the concept of a side charging AR15.

  • Jack

    New frontier, joebobs outfitters and gibbz arms all offer the same upper. There may be others out there.

  • JumpIf NotZero

    Sweet. Now only massive blinding blowback out two sides of the gun.

    I appreciate the idea of custom lowest spherically designed for pistol cal and Glock mags. But… It’s like putting knobby tires on a mustang, it’s never going to work well off-road. Pistol ARs just kind of unfortunately suck.

  • Christian Hedegaard-Schou

    Large frame lower + 10mm Glock mags + 10mm DI upper from RMW = bad-ass 10mm carbine with none of the disadvantages of blowback.

  • Ben

    This after I mated a Wilson barrel, JP bolt, and Gibbz/Spartan side charger to solve the problem.