Most of the 'shimming' is being done to fit barrels to frame that did not come on that frame. Only a few times can I recall reading here that someone has 'had' to shim a barrel from what may be frame flex/underlug set-back which created headspace issues. Now, the question comes to mind, did these few cases start with a gun that already had headspace issues, but still fired OK, and the constant pounding aggravated the problem (not unlike a revolver with too much cylinder endshake that will hammer peen the recoil shield causing more 'headspace').
I know there are some boys (and maybe girls) here that have been shooting pretty heavy loads for some time without creating a rash of 'streached' frames.
Until someone posts some real, definitive, well done stress tests (I believe some have been done) we will continue to do more than a fair bit of speculatin'............
As to this OP's situation, I am truely glad you seem to have it licked!
