new gun for teenage hunter; 5-10 150lbs boy used to shooting
.223 & .243: how much different would the 6.5  be?

assume we’re comparing 100 gr. vs 140 gr factory loads

he’s shot my .308 & didn’t complain but don’t think he’s
ready for it yet

The recoil difference between a .243 and 6.5 will be marginal. You could always split the difference and get him a 6mm Creedmoor .

He should be fine.

If you find he is recoil shy make some downloaded rounds for him.

I don’t think you will have a problem, he’s not a small lad.

6.5 Creedmoor would be a great choice, you have the option of running lighter bullets, down under 120gr, but then you can go up to near 150gr when comfortable.

thanks for the replies; the only thing having me doubt getting the 6.5 is i'd have to get new reloading
stuff and i already have a great shooting .308 that he'll get eventually.

the T/C compass still has that $75 rebate making it $225 OTD + it's easier to find (on the shelf at Academy)
so after looking at alot of ballistic tables, it's probably gonna be the .243, but again, thanks for the replies.

eta; the places we typically hunt don't have shots past 200yds

For a young hunter, that may just be your best choice. Factory ammo is cheap, plentiful and effective. Recoil is light.

Be sure to post pics of his first deer!