Which rifle, suppressor for deer?

[M4Madness]

So by part 2 would an sbr be a handgun as long as it meets part a and b

Yes, Indiana considers any firearm with a barrel less than 16" to be a handgun, but the DNR no longer does. Up until Indiana closed the loophole a couple of years ago (see part D in gunselman's post above), technically you could have hunted with an SBR in any caliber legal in a handgun.

So an ar pistol in 300blk is still good to go then

Yes.

My question: What or who determines if it is a hand gun? I looked up the .300 Ar Pistol and it sort of looks like a rifle.

Is it a handgun because that is what the manufacturer calls it?

It is a handgun because it does not have a buttstock on it.