Bob,
I can give you some specific information on my CSMC model 21 longevity or more precisely lack of longevity.
I ordered a CSMC 12 ga 21-1 3-27-06 & the gun was delivered to me in late November of 06. I ordered is specifically to shoot in SxS events & it has been shot every year since then @ events like the Southern, The UP, Metford, Hausermannn's & the Tunnel of Trees for an estimated 2500 rounds per year so lets say 25000 rounds over the last 10 years & with low pressure 7/8 oz or 1 oz loads exclusively.
I sent the gun back to CSMC in 2007 for adjustment of the trigger pulls & safety tension & to correct a cosmetic issue on how the forend was fitted. The gun was returned to me with buggered & mistimed screws but otherwise CSMC did manage to correct the initial issues.
The gun has been reliable as far as function but it is now loose & off face to the extent that a .002" shim on the hook is required to tighten it up (adjusting the locking bolt stop all the way in won't correct the loosness).
To me, 25K rounds is not a lot of shooting for a M21 to go off face & would indicate that the hook was never fitted to the joint pin properly in the first place & based on my experience I would agree with John Roberts comments.
