If the contoured mating surface of the stock isn't centered in the tang, it will appear to be tight but may not be, as you tighten the bolt you need to work the stock a little to make sure it's perfectly mated to the frame, tighten, wiggle, tighten wiggle, until there's no wiggle. A little blue or purple loctite or finger nail polish applied to the stock bolt threads will insure it doesn't come loose.
Tim