I have 10 20 round boxes of "Hi-Vel" Triton ammo. Looks to be 45 ACP but headstamp reads 450 SMC. Anybody know what I have?

It's 45 Super, for lack of a better description it's a hot version of the 45ACP.

More here:

http://www.handgunsmag.com/201...ition_1911_hot_rods/

Thanks for the link.