I built this AR45 (45 APC braced pistol) using a New Frontier lower (branded as Spartan for Joe Bob Outfitters). It uses the new Frontier upper and lower, plus a CMMG Radial Delayed Blowback with an 8" barrel. I removed the ejector on the New Frontier lower.
So I am trying to adjust the last round bolt hold open; long story short, the mag seems to sit too high. I even removed the LRBHO wire just to take that out of the equation. I am using Glock 21 Gen 3 mags. I also tried a knock-off high cap mag (25 rounder). You can see in the photo below where the bolt lugs are hitting knock-off mag. No such marks on the Glock mag, but as you see below, the bolt lugs don't clear on the Glock mag either.
The only thing that seems to work, is with the mag removed, loading a single round and extracting by pulling the charging handle. The round ejects as expected.
Is this lower simply incompatible with the CMMG BCG??
So I am trying to adjust the last round bolt hold open; long story short, the mag seems to sit too high. I even removed the LRBHO wire just to take that out of the equation. I am using Glock 21 Gen 3 mags. I also tried a knock-off high cap mag (25 rounder). You can see in the photo below where the bolt lugs are hitting knock-off mag. No such marks on the Glock mag, but as you see below, the bolt lugs don't clear on the Glock mag either.
The only thing that seems to work, is with the mag removed, loading a single round and extracting by pulling the charging handle. The round ejects as expected.
Is this lower simply incompatible with the CMMG BCG??
the bolt catches the follower in the empty mag coming out from the last round. You can see in the pic below how the tip of the follower is above where the lug seats home.
), I will be forced to go the classic bolt carrier and barrel route. The good news is I can find a 12" barrel which will easily allow this to be made into an SBR.
