Considering that the original powder for 30 Carbine was IMR 4227, you might find some of that left somewhere as it is probably rarely used today.

You are going to feel like a fool if you blow the bolt and receiver apart by using the wrong powder. These things were exploding with regularity when being developed until they got the case issue solved. I believe that there is really only one load bearing lug, the other is kind of a guide lug and probably is a safety lug as well. I bought carbine powder from Barnett years ago it was equivalent to Accurate 9.