If I had a nice 2 1/2" Gun, with good lock up n good bbl thickness
I'd handload some light 7/8ths or 1oz,low psi loads n shoot them.
I remember Bell being surprised at how little the thick waxed paper did to raise the psi on some.I think I'd use plastic.
I'd figure the service pressure ,then find a really low recipe to allow for the odd 1000+ psi spike, & then some for luck.
I say that, but if I actually had a 2 1/2" Gun, I might be a little more cautious smile
be safe lads
PS...wouldn't roll crimped 2 3/4 loads be the answer???
franc