This has nothing to do with cast bullets, but while I use IMR3031, IMR4895 & IMR4198 in heavy loads for .30-30 ,
.38-55 & .45-70 with cast bullets.
I also use IMR powders for JACKETED loads too. I load .270WIN & .257Roberts with IMR4350 for myself & a friend. Same loads for 40+years. Accuracy; 3rds into a 1 1/2" group minumum for all 4 guns with both loads. loads that are now too hot according to all the manuals.
When the new ENDURON powders came out, my buddy got a hold of a sample pack of 4oz cans of each of the 3 powders. He passed them on to me to try in our matching rifles.
Changing only the powder charges I made up 10 rds each of light, medium & max loads. Accuracy was equal with the light load of IMR4166 IN THE .257. And that was the only one of 18 loads that matched any of the IMR4350 loads.
No ENDERON powder load matched VELOCITY across the OHELER? model 35 chonograph screens.
Only one ENDURON POWDER load matched for accuracy.
He shot on a cool day (60degrees) with a 5 mile cross wind.
He started with 3rds to dirty the barrels & didn't clean until all 33rds in each string had been shot, 2 minutes cooling between shots.
The ENDURON powders in each string burned cleaner & cleaned easier in each string.
I guess cleaner & cheaper beats performance. But then I think they're supposed to be better for the enviroment.
Long time Caster/Reloader, Getting back into it after almost 10yrs. Life Member NRA 40+yrs, Life S.A.S.S. #375. Does this mean a description of me as a fumble-fingered knuckle-draggin' baboon. I also drool in my sleep. I firmly believe that true happiness is a warm gun.