Alright, got to do some shooting today, but not as much as I'd like...BUT, it's always good to get in a little "group therapy".
Sun was beating down and it was keeping the rifle hot. I had to rig up a small umbrella on a piece of pipe, strapped down to my Bull Bag on top of my Legacy bench... It was some serious redneck engineering, but it worked ok, and was definitely MUCH cooler than without it.
As for the 7977, I used .300 Weatherby load data for my .300 Ackley, since it is just basically a .300 Wby with a 40º squared shoulder instead of the rounded shoulder.
I did not realize that the specs for my case were cut to match specs (forgot my smith used his match chamber reamer with a SAAMI neck), and so the case body stays very tight with very little expansion (the same as I have talked about my 7mmRM's chamber). Anyway, so I over calculated for the Ackley, and my very first load was what Hodgdon said was Weatherby max load (usually with an Ackley, that's where I start). Well, this time I was WRONG! My starting load was 83.0 grains of 7977, and that was all well and good, but that is apparently my MAX safe pressure. At 83.5 I was getting ejector swipes... I tried 84.0, and the primer didn't look very cratered at all, but it did have an ejector swipe. However, I noticed when I shot that very first load at 84.0, my MSv2 went from 2917 to 2974... Needless to say, this is why using your chrono during load development is so vital. You can instantly spot the pressure spikes, and know you need to stop right there and back off.
So, here's my findings on 7977...
At 83.0 grains (first load tested and I hit the wall)... Even at the wall, I was pushing a 210 VLD at 2,942 MV average with an ES of 14, and an SD of 7. Which is 100 FPS faster than a .300 Wby with the same bullet and the same powder charge. This powder is CONSISTENT! It was stacking them in the same hole... Even in Alabama summertime...It's been raining for 2 weeks now, and today was the first dry day...And it was HUMID! And the sun was directly overhead heating up the guns and ammo. It was 85º with about 90% humidity at 581' elevation. It was like shooting in a swamp in the middle of July...