I don't know much about NFA and Class 3 weapons and this may be a stupid question sorry if it is. I saw a 10 round mag conversion at Cabelas for my Mossberg 500 12 gauge is it normal rules or will it make it a destructive device? Just want to check before I spend all that money.
Destructive Device: NO That mag extension kit will not make your shotgun a destructive device. It will make it illegal to hunt migratory game birds !
You only have to worry about making it a NFA weapon when you cut down the barrel. A shotgun that has a barrel < 18 inches or the overall length is < 26 inches.