Looking at Speer #14, I see now that the 300 WBY case will hold about 90 gn of
powder, and some starting loads have about 60 gn of powder, so
2/3 full.
I was wrong to broadly compare the 300WBY to my 30/378WBY, which
holds 120gn of some powders and has a long barrel.
I shoot a reduced recoil round of 50 gn of H4350, which does not fill the case.
A magnum primer and stick powder work ok, but I still worry about the
less than full case.
Full power loads in H870 or Retumbo will throw bullet far and fast,
but will bruise me after a few shots, even with a Pachmeyer recoil pad.
Most of this is range-like shooting on our property, which is harder
on the shoulder meat than a standing shot. I need a shooters bag
on the bench shots, and I do not take long shots without some form
of stabilization.
After bruising, I don't shoot well regardless of rifle until the bruise is gone.
I've put about 100 rounds through this rifle in the last two months, so
I feel that this is representative for any large Magnum.
I'm 6'1" and 230#, not fat but in good condition and strong for
my age. Played LB in college FB. Still boxing 25 years later.
Earlier remarks did not factor in fitness level, but I won't
dispute them. Fitness helps recover from magnum rifle
shooting, IME.