I do believe that there was a pressure problem of some type, and that the description of the problem is the real issue here.

My opinion is that simply having the shoulder not pushed back (as in full length sizing) could not have been the problem.

The details of our discussion are in another thread about a new guy's loading kit. The basic reported facts are:

LD was first time loader helped by his buddy,
7RUM,
partial sizing caused the problem on once-fired cases,
cases were trimmed to length
pressure spikes due only to shoulder not being set back (per gunsmith)


We were messing up the new loader's thread with this discussion and probably creating some confusion for him.