RE: .410 for deer
I remember reading an article in G&A a few years ago about a Klashnikov designed 410. This particular gas operated slug gun was quite effective on the test day and designed for Sitka deer I believe. I know of several whitetail deer that have been taken by farmers with the 410 slug, but have never attempted it myself. Like NE Hunter said, practice is the main thing. If possible you may wish to consider mounting some sort of electronic or holographic sight to increase your accuracy. Shot placement is really the only limiting factor in your decision. Also you may wish to check the regulations. Is it legal to hunt with a 410 slug in your area? With consistent practice, and patience you should be able to connect. I do not believe the 410 slug will be as comparible in design to a regular hunting bullet, so you should wait for a broadside shot.