Iharrel, its a Wildey in .45 Win Mag. Its an ..interesting gun. Gas operated, with an adjustable gas system!
In case you are interested, the guns are an LAR Grizzly Mk I .45 Win Mag, an Auto Mag .44AMP, a Coonan Model A .357 Mag, an 8" Auto Mag .44AMP, a 7.5" Auto Mag .357AMP, a Desert Eagle .44 Mag, and the Wildey .45 Win Mag.
and, they're MINE!!!!!:D
All else being equal (and it almost never is) bigger bullets tend to work better.