I used to be a firearms salesman. I would try to talk more guys out of cartridges they didn't need more often than not. If I had a guy come in, who obviously never took his rifle to the range, and wanted to go shoot some deer, but wanted a 7mm Mag because that's what his buddy/dad/cousin/brother/uncle/old-man-down-the-road/grey-aliens/voices-in-his-head said it was the only gun worth getting. I would find out where he/she would be hunting. Terrian, range, etc. and than, if applicable try to sell them a .270 or 7mm-08. I would explain that out to 300 yards, (About as far as most reponsible folks round here shoot) there would be so little difference in the point of impact, they would never know the difference. But they would appreciate the lighter recoil and blast of the smaller round. Same goes for for other cartridges. I like seeing people shoot well. If they can't control their rifle, well you know where that will end up. In my experiance, the vast majority of folks don't know what they want. They only buy because someone says so, or the name is reconizable. I also worked with a couple guys who felt the opposite. "You HAVE to buy this or that. Your opinion doesn't count, I work here, I know all. You need a .30-06 with a 10x leupold for that 50 yard shot in the bush." Or "That .338 ultramag would be the perfect long range deer rifle. 300 yards is a long way's, you need somthing that will do the job well, it should work fine" People are very opionionated, I'm one of them. In my opionion, you should shoot a rifle that you will be comfortable with, and can shoot well. If you can only handle a .223 or .243, but wan't to hunt only deer, don't buy a .300 Win mag. If you can handle a little more recoil, and have time to shoot your rifle alot, maybe that .300 isnt such a bad thing.