Flip a coin. Either round can be loaded for mice to moose and anything in between. For field use I'd go with 240-250 gr cast over 10 gr unique for 1000 fps and call it a day. The one thing that would lean me towards the 45 is getting the convertable to shoot 45 acp out of.
If you're planning to load up the 300 gr bullets to 1200 fps then I'd highly recomend the bisley as it's grip is much better for dealing with heavy recoil.
