With the shortage of available powders for reloading, I found I have about 1/2 lb of RE7 that I'd like to burn up.

Any ideas? I have the following cartridges that I load for now that it might work in.

256 Win Mag
257 Roberts
7x57
357 Max
204 Ruger

The goal is plinking / varmint loads.

Seems to me the 204 would be a good match.

RL7 is the most accurate powder for my .222 Remington. It is also very accurate in my .300 Savage with 125 and 130 grain bullets. You should be able to find some loads with lighter bullets for some of those you mention. It is a very fast burning powder and not very versatile, but keep looking and you should find a few loads.
joe

I found loads listed for my 22 Hornet, at less than 11 gr per load that 1/2 lb will last a while.

Also found some for the 204 Ruger with 32 gr bullets, but I load 45 gr.

I'm going to load some 257 Roberts with 75 gr bullets. As a guide my Hornady manual lists loads with 4198 and 3031. RE-7 is between these two in burning rate. This should be a starting point.