Jason,
In a word, yes. It isn't a problem with the bullet itself but rather an incompatibility between the thin jacketed "Hunting" 105 and what you're doing with them. Several years ago, long 6.5 bullets made on J-4 jackets (not just Bergers) were occasionally coming apart in flight when driven hard out of long barrels with slow powders and most often through barrel throats that were a little over the hill. Berger researched the issue and introduced bullets identified as "target" with thicker jackets to better resist the accumulation of insults that long range shooters force their bullets to endure. It probably takes a 6/284 or 6 AI to cause a 6mm Berger "Hunting" bullet to pop in flight even with all the other insults in place. A 6BR or 6BR improved is not likely to produce this result. The answer for you is just substitute Berger's "Target" bullet with the thicker jacket for the more fragile "Hunting" bullet that is popping in your setup.
Greg
