That load might be under 50,000CUP or CIP, but doubt very much it's under 50,000PSI. In that round, 48,000CUP is probably 55,000PSI.

The .376's maximum working pressure will probably be in the vicinity of 64,000PSI. It's capacity is just a couple grains higher than my .375/06IMP, which is 80gr. total water capacity.

I suspect 68.0gr.BLC2 might run some 2,650fps + from your barrel and tighten things up a bit. Your barrel seems a bit slow. 68.0gr. is what my 9.3x62 (78.0gr. capacity) likes and runs 2,675fps/270gr. in a 22" bl. That might be too high for some other 9.3x62's though as it's too high by 2gr. for my .375/06IMP - just goes to show you all rifles are different. I worked up to that from a 56.0gr. start.

What barrel length, Bonanza?