I use 175 SMKs in a Remington 700 and started getting pressure signs at 44 grains, which was a bummer cuz that load was shooting great groups. I am now using 43 grains and getting no pressure signs, although the groups aren't quite as good as they were at 44 grains.
As for primers, the BR primers, according to CCI, are the same as the regular ones, just more consistent. They say they use their most experienced people to put them together and take more time and care so that they are more consistent from one to the next. I doubt anybody but a benchrest shooter would notice the difference between a regular primer and a BR primer. Especially at 100 yards.
ETA: From the CCI site (BTW, I am fairly new to reloading, but I seriously doubt the last sentence):
Only our most experienced skilled personnel put the priming mix in the cups, so you get the same flame, shot after shot. We also use specially selected cups and anvils for added consistency. An independent researcher identified the use of CCI Benchrest primers as one of two factors that were the most significant contributors to tiny groups. We can’t add much to that!