Feeding issues with custom build

[Klem]

If the mags have fed properly previously then unless you are trying a new bullet it is probably friction; concentrate on pushing every single round to the back of the mag as it only takes one or two rubbing against the front to slow that follower down. We don't have, or leave too much clearance in this calibre so it doesn't take much to load too long, or not have all rounds loaded properly. Knock that mag after loading and rounds will drift forward against the wall. I find this happens a lot with heavy Blackout rounds, and the heavier the bullet and the more you load, the more you need all that magazine strength.