Zero......but I hate saying that as it is always possible. When your are bending them you can feel the resistance. Some you could push with a single finger I swear, others are very difficult to move but those are usually the fore mentioned pistol grip/American walnut guns. The Brits have been doing it for hundreds of years and some folks think they know a thing or 2 about stock work on fine doubles across the pond.
Steve

Firearms imports, consignments


[Linked Image from i.imgur.com]