If you want a non corrosive powder, better get the Savage.
A few years back BlackMag3 came out. In the BlackMag3 ads, they described this powder as "non corrosive."
I noticed that Cabelas, where I bought my BlackMag3, did not describe it as "non corrosive."
To test it out I fired one shot with my cap and ball revolver. I let it set for 2 weeks before I checked it. The cylinder and hammer were all rusted up! Thank God, I had run a couple patches down the barrel after I fired it.
It took me 3 hours to clean up that pistol and it is still not quite right.
777 and all the other black powder subs will cause rust if you don't clean up after shooting them.
I have fired the Savage, and let it set for a year without cleaning, no problem.