I've been doing my homework learning about Doubles for a year or two and I'm debating which caliber for mine. So I thought I would test the waters from this august group. The rifle will be for animals other than elephant so I'm going to stay under a .50. I'm looking at the following" .450/400 NE 3" .450 NE 3 1/4" .470 NE Opinions and thoughts? Pro's and cons? Thanks.