Blackhawk isn't my cup of tea with the whole button to release...
I recommend searching http://www.copsplus.com
belt style safariland the for S&W 457
TBH, I think Blackhawk holsters are junk. Also, if you're serious about OCing everywhere, buy a duty belt + belt holster + belt keepers. That way you can take the gun off with the belt attached.
A duty belt goes over your regular belt, you do not loop it through your pants. The belt keepers go around both belts.
There doesn't seem to be much of a selection for your 457, but I've just went through a couple pages on the search.