sounds like that would be more of weak hammer spring to me, I had a similar problem with their 38's turn out to be the hammer spring, I talked to a rep at ultra max they said they use either winchester or cci primers those are the two hardest primers around especially the cci primers, My revolver shoots winchester ammo without a hitch but when I started handloading I used cci primers in my loads and the same problem began all over again I changed out the hammer spring and now it shoots the cci primers with no problems.