I find the laundry bag / duffel bag technique works the best. Make sure gun is unloaded, take out bolt assembly, take out screws.
Get your big laundry bag full of dirty laundry. Grasp gun by the barrel or forearm beat all 4 sides of the butstock against the laundry bag.
You also can beat the stock on a pillow, on your bed, a couch, or a padded stairway rug but I find the significant others tend to get upset with that.
The stock should wiggle right out.