I am in my 70s now and use Grocks for carry guns, usually a G19 in 9X19. In a home defense gun it is just as easy to go with a full size pistol with red dot sights. Pretty easy to find a G17 to shoot at one of the ranges that rents guns so your Dad can try before buying.

I would stay away from trade-in 40 S&Ws as being potential kabooms. When I tried a .40 carry gun I found them to be very snappy in recoil too...

jim

LCDR Jim Dodd, USN (Ret.)
"If you're too busy to hunt, you're too busy."