Here's the situation:
gun: Browning A-bolt, .338WM, 26" barrel
load: 225gr. Barnes TTSX, 71.0gr. Reloder 19, WLRM primer, R-P case, COAL 3.370 which is 96 off the lands, chronos at 2830.
I have been shooting this load for over a year, it has been at the range several times and hunting more than once. Never any sign of
pressure issues. Accuracy has been excellent.
I decided to try to develop another load for same rifle:
load: 200gr. Accubond, Reloader 19, WLRM primer, Nosler case, COAL 3.366 (same off the lands as the TTSX).
I loaded a powder ladder from 71.0 to 76.0 in steps of 1.0 up to 74.0 and 0.5 after that.
Nosler powder range for that load (7th edition) is 72.0 - 76.0.
Hornady, Lyman, Speer and Lee all have similar max loads (althrough Lee is a bit more optimistic at 78.0).
The first shot, 71.0gr., gave a normal report and chronoed at 2799, slightly lower than the 225gr. with the same charge.
Upon inspecting the fired case, I observed a very flat primer with some black residue around it. There was no cratering
and no bolt impression in the case head.
I would call that an early high pressure indication. So I put that load away for the day.
Now, powder charge is well below the expected maximum, and the same charge that behaves well with a heavier bullet.
Also, the lighter 200gr bullet seems to be flying slower than the heavier 225gr. in a similar load.
I am using a different case. Nosler brass may be enough thicker to cause somewhat higher pressure, but this much
of a difference?
What am I missing here?
