Jim,
I have Alliant load info as follows-
Bullet 150 GR. SIE JFP, C.O.L 2.525"
Reloader 15 36.0 grains for 2450 FPS out of a 24" barrel and 40,600 PSI
Bullet 170 GR. HDY JFP, C.O.L 2.545"
Reloader 15 34.1 grains for 2330 FPS " " " and 40,500 PSI
Both use Winchester brass and primers.
I would think a 1955 era Marlin would be a "modern" firearm but am no expert on Marlins.
Here's what I copied from JB's "Handloads That Work" article-
".30 WCF: I still use the same load
here, partly because RL-15 is an
even better powder. A 170-grain
bullet and 34.0 grains gets 2,100 fps
out of most 20-inch carbine barrels
and can push 2,300 fps from 24-
inch rifle barrels. "
