RE: .243 for deer
Speaking form experiencethe little .243 is a dynamite deer cartridge with the 100 gr. bullet loadings. I've shot many deer with this cartridge and only one ever needed a second shot. Most of the deer dropped where they stood. I guess the little bullet delivers a good bit of hydro-shock. The only other cartridge I've found that seems to drop a deer faster is the .270. I would bet the 7mm mag also would do the same but I have no experience with this chambering.