well i can tell you that an SC1 would fit into that, regardless of the make, im currently holding an sc1 blank in my hand and the milling will fit. i for one can only tell the difference between kwikset and schlage. but if im looling at the key, i can tell what lock or blank it is. locks are harder for me. and like this lock, i imagine a few different blanks can fit it.
Checked the AR1 keyblank at the shop today and it's kinda the reverse of that. It actually looks more like Russwin RU4. Or Elgin, like magician said. It's not SC1. I promise.