Mine was in a G2, very accurate, took a nice boar with it. I'd recommend the .50cal. though. You could load .357 cal bullets in duplex sabots if you want light recoiling ".45cal" "performance" etc... etc... 50cal bullet selection far surpasses the .45. The 50 will do anything the 45 will do plus a whole lot more. 50 cal is a little lighter to, due to the bigger hole in the barrel, makes for a well balanced and versatile set up.
You can't go wrong either way.