I have a 280ai with a 26" carbon benchmark tube 1:8 love the rifle shoots 143 HHs with H4831 .5-.75 at 3180 fps. and 168 LRABS with h1000 to .25" and 2850 but picked up a 6,5 saum so thinking of making the 280ai my dedicated elk rifle or bigger game. I am thinking about trying either the 155s but really hope to get the 172s to shoot. My question is with less pressure what powder should i be trying with 172s? I guess i have the same question as the original owner gave me some 123s for the 6.5 saum as well. I use h1000 in that. thnx