Yes, it's true . . . SRP pockets hold up to pressure better than LRP's. It's really not hard to understand why given that smaller pockets means there more material/mass for the pressure to act upon. When using hot loads, the smaller pockets will not loosen up as soon or as easily.I believe the 6.5cm was designed with a LRP. I've not found ANY difference in accuracy and I've tested it quite a bit. LRP are more reliable in some more extreme conditions also. Lapua has said that they tested it and they found SRP to produce better accuracy so they changed to using SRP, so there is that. I think the main reason some guys run SRP in 6.5cm is because they think they can get away with running hotter load with SRP and not effect the brass life as much as well. I think.... I haven't ever tested that nor seen any testing for that so I don't know about that, maybe it's true maybe it isn't.
Yes, it's true . . . SRP pockets hold up to pressure better than LRP's. It's really not hard to understand why given that smaller pockets means there more material/mass for the pressure to act upon. When using hot loads, the smaller pockets will not loosen up as soon or as easily.
SRP's do have a different ignition temperature, so they'll not perform exactly as the LPR's. Which works best depends a lot on the particular powder one is using and how much of it for a particular projectile. The only way to find out which works best for your load is to test and see what kind of results you get.