I had a Perazzi sporting clays gun bent for cast off by Jack Rowe about 20 years ago & I once observed a gunsmith bending a pistol grip Beretta 680 series field gun for both cast & drop at the Grand American when it was held in Vandalia OH (can't remember the gunsmiths name).

From this I would assume that some draw bolt guns can be bent but I've been told that competition guns with thick pistol grips can be difficult to bend.

I would talk to someone who does a lot of stock bending.