FWIW, I have used lp primers in different rifle calibers, just start low and
work up just the way you should do anyway, have even reamed primer
pockets in some pistol brass to use lr, start low and work up.
Have done the same thing only a lot more with sp and sr, don't need
to ream the primer pocket deeper with the small primers.
Did an experiment with the 454 Casull, very high pressure loads, with sp
and sr primers, you would not believe the results, sometimes the small
pistol primers would be higher FPS, same in the 9mm.
The key is use a medium burn rate powder, that helps.
I use sp regularly in the lighter 454 loads, most pistols don't need a large
primer either.
We may all have to get real creative some day, one reason I like guns that
shoot many different cases, and don't forget the boolit molds, they are only
twenty dollars each.
Last week I shot three different cast boolits in the 223 with good results and
three different cast boolits in the 30-06, most rifles are great cast boolit guns.
For those that like subsonic loads all you need is a good fit cast boolit, even
in the 30-06, about five to ten cents a shot.