I have the same rifle but haven't had the problem you describe, I took my rifle apart and tried to make it not fit just to see if I could diagnose the problem. The only thing I can think of is maybe the screw that holds the barrel clamp on is somehow loosened itself a little and is causing the stock to teeter on it. Whetever you do, don't try to tighten the star screws near the mag well in order to tighten up the gap at the front of the stock. This is normal on this rifle and mine has about a 1/4 inch gap there.
The only thing I really dislike about this rifle is that the rear sight (where is attaches to the barrel) likes to slide from side to side ever once in a while. It doesn't move all that much and it takes months but it seems to be a pain in the butt so I put a Simmons 3-9x32 scope on mine so I didn't have to rely on the iron sights. The part that moves is next to my thumb in the pic.
Otherwise, this rifle makes a good squirrel rifle and mine has killed about 100 squirrels in the couple of years that I've hade it.
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