After spending a bunch of time trying to shim the scope mount so that the scope's bell wouldn't touch the barrel I gave up on the original scope and put on a 4X Leupold borrowed from another gun.
Finally the light dawned that I was a major error factor and I bought a front and rear shooting bag so that I was shooting from a really stable position instead of just resting the front on a padded toolbox.
My first sample of my own handloads with round nose 150 gr bullets put 5 into 3" at 50 yds.
The gun is just fine and the scope mount is fine. With this scope I can tune the load then when that's stable can go back to trying the original scope to see if it's broken or needs different mounting.
Gun kicks hard thru the steel buttplate so a LimbSaver is next.