H4350 is hard to find, but IMR 4451 is not. I have tried the 130 gr Berger AR Hybrids with RL 16, H4350 and IMR 4451. The clear winner was IMR 4451 in the 43.6 to 44.2 range with no pressure signs @84* F. This confirmed some ladder testing using all three powders the previous week. I'm going to load a bunch up at 44.0 gr and hope to shoot them later this week for groups @ 100 and 200 yds as well as separately velocity with my Magneto Speed Sport. The image below in new, sized 165.4gr Lapua cases with CCI 450 primers and the bullets were ~0.045 off the lands of my 20" Tikka T3x CTR. The pic is a cropped version of the larger test of the three powder which when I tried to post a note said it was too large.These loads were safe in my rifle with no pressure signs on the cases or primers nor did they have any stiff bolt lift, but may not be safe in your rifle! The max load listed by Sierra for their 130 TMK is 43.7 grains so start some below that in your rifle for safety.