I have been smoothly reloading quite a few calibers, 3006, 308, 9mm, 40, 45acp, 45gap, and I thought I was rolling along pretty well until I got to 223. I have been getting a case mouth flaring problem about 1 out of 10 223 cases. What happens is the case mouth flares out and jams in my gun. It is easy to see which cases have the problem, pic below, but I bought a case gauge to test every round I reload to avoid jams. I have tried using all the same brass and same bullets, and then tried another brand brass and bullet and get the same result.

The bullet seating die is about 1/4" from the bullet holder. If I ram the lever too hard it pushes the neck down into the shoulder. I have tried moving the bullet seating die down/up a tiny bit and the problem is pretty consistently ever 8-10th bullet. It is so frustrating to have to bang out bullets and resize/reload. Any suggestions would be greatly appreciated.