On the other hand, I was told, and later confirmed with a call to the factory rep, that the Alliant Reloader series powders all had decoppering properties (except for RL17). I've used RL15 for about 8 yrs now in highpower, shooting and cleaning MANY times. I can tell you, I had to confirm that what I heard was true, because between my 223 ARs and my 308 M1A, I was continually cleaning copper from my bores. Patches were always coming out blue. Does Alliant not put as much Bismuth, (or whatever the "magic" ingredient is) into their powder, or is it another variable, such as cartridge, powder level, bore condition, etc.? Any input or experiences would be appreciated. Thanks!