
Smoke

I am well aware this does not help you in your quest. However, If I may (and I am) I must suggest you not bother with 45 Colt. Your current caliber (38-40) allows you to shoot your rifle with about zero Blow-By of gun gas. The Rifle probably shoots squeaky clean.
I can attest, unless you get into the Case Annealing business, you're going to begin fighting Blow-By with the first 45 Colt you fire. Without annealing, 45 Colt cases WILL NOT expand to seal the chamber and you WILL get Blow-By. The only other suitable choice besides annealing, is to start with 44-40 cases, fire formed to 45 Colt.
If your happy with your 38-40, Stay Happy. If you rebarrel to 45 Colt, you're not going to be happy at all.
Let Us Be Safe Out There