.243Win And Deer
I have been in the process of setting up a 16" bbl pistol chambered in .243 for the Flah-Dah sized deer that we have down here in(you guessed it) Flah-Dah. This is the very first .243 caliber weapon that I have ever owned and/or reloaded for, so I have been doing some fairly extensive research.
I assure you,your son will be able to handle the .243 just fine. To me,a little more crack vs a bang,definitely no more recoil. If using factory ammo,as Mike stated,use upwards of the 100gr bullets. My recommendation would be in the 90-100gr weights. Or you could go even lighter if using one of the "no lead" style. Stay away from the lesser weights because I(for one)consider these varmint bullets.
Remember also,the .243 will adequately handle any deer residing in Florida. The bigger hogs are another story. For these critters,heavier,well made/designed bullets are mandatory. So is shot placement. Google -->images,hogs anatomy,have your son read up/study up on this. There is a "sweet spot" to hit a hog,especially the larger ones. Then.....there is several bad spots that would normally be lethal on deer.
The 80 pound hogs are fairly easy to kill....a 300+ pound boar is altogether different.
Have fun with that .243. -----pruhdlr