Great thread! I’ve got some 280gr A-frames I want to work up a load for as well as the 250gr AF. I have “all” powders so I can go to “THE” powder, whatever it is. CFE?…
Kinda depends on how much temp sensitivity you're willing to deal with. I'm leaning toward Big Game or RL15.5 for 310 woodleighs. PP 2000-MR is sick for speed and accuracy for 250's and is basically equivalent to Big Game under 310's (Big Game had less ES).
But for me under 250's if I work up a 2000-MR load in summer here and hunt in winter in a mountain state (100 degree temp swing) MR-2000 changes speed enough to drop out of the node and act funky (and very radically change my POI at 300 yards). It all still went bang, no hangfires etc, no change in recoil, but I'm changing powders. Earlier this week I ran the Labradar on last year's 2000-MR loads...they were 2560 fps last fall (mild temps) and earlier this week (hot temps) they were 2650fps (90 fps increase)
All of which to is to say...I keep collecting data that 2000-MR is very temp sensitive. Plenty of people love it and I did too until the above mentioned issues and it might not be an issue for you in the PNW or anywhere else with moderate temp swings. CFE I have but haven't used...but I have possibly heard that it has the same temp sensitivity as PP 2000-MR.
As far as yer 280 A-frames...I used both Big Game and RL-15.5 (new stuff) under a 310 Woodleigh...
With them 310's, RL-15.5 got to 2240 before it started showing pressure (20" rifle) and Big Game got to 2260 or so (same as 2000-MR). Didn't work up carefully in my 26" Whelen, just fired a few extra rounds, they showed less pressure than in the 20" and were getting 2375 fps with round primers. Again, that's a 26".
310gr at 2375...should be a great load for the 75 lb deer we have here.
