I have a B&T APC-10 Pro and I would like to build (or buy complete) a lower cost reliable 10mm AR pistol. The Banshee MK10 seems to be the best but looking to get something cheaper. Aero and Stag Arms both had 10mm AR pistols in the works but didn't end up following through.

Any good options out there? Did some research but didn't find much.

The B&T APC Pro isn't reliable?  I'm curious because from time to time I've considered buying one.

Olympic Arms had a blowback upper that was compatible with a standard AR lower, but it uses proprietary AR dimensioned magazines.

You could order the mags direct from Olympic and might still can. Apparently they were still in business even after rumors of their demise were being circulated.  I ordered a couple a couple of years ago and got the impression that they were making them to order. Sort of an injection molded clamshell+screw build design where the 10mm cartridges single stacked and biased to the front of the magazine.

Mine has been reliable, but the mags only hold 18 rounds, so I think that makes it more of a range toy/novelty item than a serious self-defense item. The mags are expensive enough that it’s hard to justify stockpiling a normal number of them.

I’d love to see a 30+ round 12” gas design with dead-nut reliable stick mags. But my concern is that a proprietary magazine is always going to be the limiting quality of the design.

It's a great gun. I just want a second one that costs less than half as much. There's not very many options out there so it must be a complicated design to make reliable. Years back I remember seeing Stag Arms announce one at shot show and then never making it to market. Same deal with the Aero Precision version.

I just orderd 10mm lower from 80%.

I think BazookaBros makes one but its pricey