I've killed more hogs than I care to count with .270, 7mm-08, .243, and even a few with .223 and a few more with a little ole .22-250! I dare say that a .270 will drop Hogzilla where he stands with proper placement.

As far as the posters question, since you already have him working well on the .270, then by all means stay with it. If he (being 18 he probably will) wants something different, I, like several other posters, am a HUGE fan of the 7mm-08 for whitetail and even for Elk at reasonable ranges out to 250. I personally feel that the 7mm-08 is what was really intended (in ballistics) for the .308 to be. Minimal recoil, more speed than you can shake a stick at, HUGE bullet weight variety as well as several bullet profiles. The 7mm-08 is a reloaders dream. Get both of yourselves into reloading and you will find a whole other realm of shooting sports being opened up to you.