IMR 4350 is not so much "inadequate" as it is "not best suited" for the 308Win
(And was that "52 grains" above a misprint?)
I went to Quickload and set up w/ a 175SMK for which I arbitrarily chose a
55,000psi limit (max pressure ~60,200). Then I ran a powder table search
for best performance as defined by maximizing case fill, velocity, and %burned.
(Note that Quickload's "105% case fill" is about where light compression starts.)
This is the result when using light compression as the upper limit and 99% case
fill as the lower, then sorting on velocity:
THESE ARE NOT NECESSARILY "RECOMMENDED" LOADS
THESE ARE NOT NECESSARILY "RECOMMENDED" LOADS
IMR4350 fell outside of this window with 109%fill (47.8gr) 2,623fps, 94.4% burn for 55,000psi
BOTTOM LINE: Even for heavier bullets, IMR4350 is not (ballistics-wise) a top choice for the 308Win.
Useful... certainly. And if it shoots well in
your rifle, go for it (Unless it's an M1 or M1A).
Velocity/efficiency isn't the end-all/be-all when accuracy is your guiding principle.