I am going to try both Goex and Pyrodex Select in my new 58cal. I am planning to shoot max loads of 120gr Goex in it to see how it shoots. My question is will 120gr Pyrodex be safe or should I reduce it at all?

If the rifle will accept 120 grains of black powder, then it will also accept 120 grains of Pyrodex. I would personally start out at 90 grains and then work upward. If you can push it all the way to 120 grains and still have accuracy, more power to you.

It sounds like a lot of fun.

I was just wondering because I remembered that chart you posted a while back.

I also have another question. I have heard Pyrodex is more corrosive and harder to clean than Goex. Is this true? What about with Select?

Pyrodex is MUCH MORE corrosive then Goex, or any other powder out there. When shooting Pyrodex make sure if you shoot it, you clean it. The Pyrodex Select is just as corrosive as the RS. The only difference between the two is the Select is more uniform in grain size because of an additional couple screenings.