This may sound silly but how about using a light dab of blue loc-tite on the side of the primer pocket to hold the primer in place. Never tried it but Im sure someone has on here.
You know what, I ordered 5K yesterday and they sent me a notification that it shipped in less than 24 hours with a tracking number. Hats off to them for being on top of things.
I have both. The JP does everything the KAC does but shoots smoother, more accurately, and the fit and finish is a couple steps above. JP all day. My SR15 sits back in the safe gathering dust. More of a collectors piece at this point.
Im interested. What gunsmith built it ? Do you have the test target ? if you do can you post a picture of it along with a piece of paper with your screen name and today's date?