I crimp everything.
I built and used hot 296 loads with 300-325 grain lead bullets for the .44 mag for several years; used them a 4" Model 29. New Starline cases, turned-down expander. There's no way those bullets would stay put in that revolver without a serious crimp. The 6th round in the cylinder would creep. I saw the exact same thing with heavy 325's in the .45 Colt, when fired from the 5 1/2" Blackhawk.
For the loads mentioned in the paragraph above, I eventually went to a two-stage crimping operation, using a Lee FCD and finishing with a 'bump' into an RCBS roll crimp die. The crimp made the difference; the slugs stayed put after that.
Talk to Buffalo Bore, Garrett, Corbon or any purveyor of heavy hunting loads. Ask them if they run a heavy crimp on their loads.