The NEF "Handi rifle" line is similar to the Encore however it's only intended to be used as a rifle. The Handi rifles are very inexpensive and purchasing another barrel in a practice caliber would be an easy selling point. I would also suggest that you consder a scout style scope mount as these are intended to be used both eyes open. I know you said he's blind in one eye however this type of scope lends itself to less than perfect eye alignment more so than traditional mounts. Another fine option is the red dot type of sight which would not offer magnification however the confidence inspiring red dot might make shooting more fun for him. As for caliber, I'd suggest something sized appropriately for the intended game. You can't go wrong with a 30-30, 30-06, 308, for deer etc. However, if he's going to limit himself to shorter ranges (under 100 yds) you could consider a .44mag rifle. Ruger makes their deerfield carbine semiauto, Marlin and Rossi both make .44mag lever actions all of which are drilled and tapped for scope or red dot mounting. I hope this helps.