I think we have failed to mention here that the case expands in the chamber sealing it. If the gun is properly headspaced then in theory there would be no backthrust. If anyone here has mechanica or likewise software, do us a favor and produce a force vector analysis and end this debate. Now to the crux of the debate: why do some guns come loose with high pressure loads and some don't? I can't say - but every loose gun I have ever seen was dry as a bone, no grease on the pivot.

B.