The no SKS thing has got to be a range rule. Appleseed is all about teaching you to shoot "what you bring" up to 8mm Mauser.
Most of the instruction is at 25 meters (82') with 22s being the recommended platform. This saves on the cost of ammo.
I have seen just about any rifle you can think of at an Appleseed event.
If you have not been to one, GO. You will not be disappointed. They are not a competition, they are geared to teaching you the skill set to be able to hit a man sized target at 500 yards, the Rifleman's quarter mile.
Go to Appleseed Project Home
for more information and a location near you that is hosting an event.
Appleseed is a non-profit, all volunteer group, teaching our fellow Americans of our Heritage of Rifle Marksmanship.