I tried the new load today at the range and the wind was 25-40 MPH.
Once I found the zero at 385 meters, the load shot very well bucking the wind. ( 200 grain RNFB FMJ's) Velocity seemed to be normal and I will try them over the chronograph to see what they are really doing. No unburnt powder in the barrel. Recoil was what you'd expect. The brass did not grow,nor does it show signs of incipient case head separation.
One of the rounds had been reloaded five times by me so I think I may have solved the problem.
In previous loads I had tried IMR-4895 with 150 grain bullets, IMR4350 with 200 and 220 grain bullets and Reloader-15 with 175 grain bullets.
I may have bought a bad lot of brass. Today's brass is much newer than the bulk brass I bought years ago that fails.