I do as keith described. I don't lash the gun down to the table, rather I put a couple of bags of shot on the muzzles. My last attempt was with my new little [ Turkish ] Dickinson 410 SxS. It has a through bolt, bent, but a week latter was back to where I started. A friend suggested cutting the through bolt and welding in a 1/4" universal where the wrist is. That way the bent through bolt wouldn't be putting pressure back on the wood. Hell, I don't know - could be worth a try.
This is interesting to me, Paul, because my Dickinson is stocked a little too high for me, too. I get by it by adding a lace-on pad to increase the LOP enough that my eye gets down to the rib, but it's still not like I prefer. Do you think it's the through bolt thats bringing the wood back, or just the wood itself returning to it's equilibrium? And, how much did you move it? And, (sorry for all the questions) what did you do about the long tang on the triggerguard? I can see how it would push upwards if not re-inletted, or bent.