RE: .410 for deer
TOONS, I'm a 410 freak. I own and shoot several, but only for rabbits, birds and squirrels. I have shot several slugs through mine, and the ballistics aren't bad. The amazing thing is the small amount of drop in the slug at 100yds. If you shoot premium shells, the slug will only drop about 7" at 100yds. Sure seems like it would be more than that.
That said, you are only getting about 600 ft-lbs at 50 yards. That's plenty to kill a deer if the shot is in the right place. I'd hate to hit a 250lb buck square in the shoulder with that little amount of energy. The penetration won't be great...and there's not enough energy for shock.
The 410 will kill deer. I've seen it. However, if you can move up to a 20 or 12ga, I would.
Good luck!