gun size or cal.

I think the .243 is an excellent all-around deer cartridge. I own a .243,30/06 and 300WSM and with correct bullet placement, the .243 kills just as dead as my 30 cals. without the recoil. I have an uncle who has owned a .243 for 45-50 years and has MANY deer and coyotes under is belt. He is an excellent shot and drops mulies and whitetails in their tracks.

Sounds to me like son is trying to get dear old Dad to spring for a new gun. Hope it works for him, but I don't think he really needs it.

It's always fun to break in a new gun. So getting a new one is not always a bad thing. Giving the state of the economy, gas prices, etc. I would hold off buying any high $ items right now. Unless he can find a great deal on a used gun. Personally, I would take a used gun over the new ones anyway.

There is nothing wrong with the .243 Win for deer. Out to 300 yards it will kill deer as dead as any magnum and be a lot cheaper to shoot. It will also work great as a varmint rifle in the off season, allowing the shooter to become more intimate with the gun, learning what it will do at different ranges. If he is leaning towards a magnum, I would definately take the .243 Win.

Now, if your .243 Win is a varmint gun or heavy barrel configuration, I would get a new gun. I have no desire to carry a 12 pound gun mile after mile, over hill and dale looking for a deer.

243 is a deer slaying machine.
So, either tell him he can use your 243 or buy his own dang gun . lol . . . or else just use it as a reason to buy a new gun! Sweet!
I have seen deer killed with smaller calibers and have killed them with larger calibers.

If you hit a deer in the lungs/heart with a 243 it will surely die, no two ways about it, dead is dead.

If you want it to drop in his tracks, well use something bigger and heavier . . . a 460 Weatherby Mag would do it for sure. But who in the heck wants to shoot that round???

Some guys kill coues deer down here with a 22-250 at 300 to 400 yds