Tre, I had him put about 300 rounds through my 870 this Spring...included shooting slugs and sporting clays.. And I emphasized shooting when the first step was to put the safety off; nothing worse than to pull the trigger and nothing happens. So he is familiar with the 870.
This was not combat training. I didn't have him practice bringing the gun to bear from a slung position...but it's enough for this summer. I've asked him to put some boxes through the 870 once he gets to Haines. I'll have more time with him this Fall.