If you're just going to buy the cheapest shells you can get, then 3" groups at 50 would be about as good as your rifle can shoot. If you get some fairly respectable shells, then sub 1" at 50 would be quite attainable. I agree that any variant scope on a .22 LR is a little overkill, but a scope on one is by no means ineffective. I even have a 4x20 tasco [about $8 at wally world] on my .177 air rifle. So might say it's a waste, but I've killed the same number of squirrels with it with less than half the shots as with open sights on the same rifle. I do agree, an older rifle, especially a mosberg, will be more accurate than what most people buy today.

GOTTA LOVE THAT MARLIN MAGIC!!!!