Scooter123 hit on something I discovered years ago when shooting Rainier 148 DEWC over the standard cast lead data of 3.0gr of Bullseye.
I was having bullets getting lodged in the bore of my 4" Model 19 barrel. I never had any problems with cast lead bullets in this revolver. I checked the diameter of the bullets with a caliper, and it measured .357", and I was checking my powder charges for accuracy using a scale. I didn't measure the B/C gap on my model 19 however, and that might have been excessive and contributing to the problem...I really can't be sure.
Anyway, the copper plating seemed to offer greater resistance as the bullet moved through the bore, and so I found it necessary to increase the charge to 3.3 gr of Bullseye to finally overcome the bullet-lodging problem.
I contacted Berrys a few years ago, and they recommended using low to midrange jacketed data.
Unless using their "thick plated" (TP) bullets, Rainier says to keep velocities below 1250fps.
Accurate Arms (now Western?) had, in 2005, some data for the use of their powders specifically with Rainier bullets, and I printed most of this data except, unfortunately,
for the .45ACP.
SteveFi mentioned that Western now has data available, so I'll need to check that out, since I have some Berry's bullets, but no published data specifically for plated projectiles...I've been kind of guessing at loads for some time now, since I don't have a chrono. handy to test velocities, and because I haven't used cast lead data since my bullet-lodging incidents in the past.
I know you're going to come up with that "perfect load" for Rainier bullets in your pistol, and it should be fun finding it.