Yes it is a handgun and therefore you need a LTCH.
IC 35-47-1-6
"Handgun"
Sec. 6. "Handgun" means any firearm:
(1) designed or adapted so as to be aimed and fired from one (1) hand, regardless of barrel length; or
(2) any firearm with:
(A) a barrel less than sixteen (16) inches in length; or
(B) an overall length of less than twenty-six (26) inches.
Does indiana count the black powder pistol as a handgun?
Yes it is a handgun and therefore you need a LTCH to carry it off of your property.
They aren't considered as firearms by the Fed when you purchase them.
Look at Indiana Code 35-47-2-19
Under what circumstances? Carrying? SVF? On school grounds?
It depends, sometimes yes, sometimes no.
Look at Indiana Code 35-47-2-19.