I had also noted that the 300BO just looks real good for a AR-15 pistol with a brace. Next thing you know, we spot a PSA deal on a 8.5" 300 BO pistol kit with the nicer brace. So for the last 3 weeks, I have been working on getting ASBB HF Red PC coated cast bullets to work.
Feeding was a major problem for short bullets with the standard M4 feed ramps. I did some work on the feed ramps, and improved short bullet feeding, but it is still not great.
My Lee 170s seemed to work better and the longer the round the better they worked. Feeding is just "better" when the tip bullet of the bullet is inside the chamber before the rear of the round is released by the magazine. I do not use gas checks so the long seating (base of bullet even with base on neck) did not have the brass holding the bullet as secure as I wanted. I cut the gas check step out of one cavity and now I have a "Lee 180" plain base that is looking like a good fit for this application.
Last edited by P Flados; 05-22-2019 at 09:59 PM.