However, on the 3" chamber issue, you might note that the load for the 3" 20ga back when those early Parkers had long chambers was significantly lighter than the loads we shoot in 3" 20's today. Which might mean--just in case the guy with a vintage 3" Parker wants to shoot MODERN 3" shells--that he might want to have it proof tested with heavier proof loads than the ones used back then. Or else maybe he ought to stick to loads appropriate to the proof pressure to which the gun was originally subjected--which would likely mean something with somewhat lower pressures than today's 20ga service pressure standard of 12,000 psi. Which, by the way, applies to both 2 3/4" and 3" shells.
Here-in lies the problem many are Skirting over & avoiding. As it stands I can use my 3" gun which happens to be a 16, with the loads for which it was intended, I don't need it proofed. The stated purpose which brought up this whole topic was to "Protect" the unknowledgeable & unknowing.
The only way of doing this would be to proof the guns with the maximum load available for the length chamber the gun possesses. The vast majority would indeed "Pass Proof". This then would tell the "Unknowing" they were quite OK to be fed a regular diet of the stoutest loads available off the shelf. We would actually be doing them a dis-service to do this, rather than trying to educate them.
The best thing to do with mandatory proof in the US is to
"Let it Go, Turn it Loose" while we still can.
It should also be noted that lengthening a chamber does not Automatically render the gun dangerous. There are large numbers of American guns which have ample steel in the chamber area to render them OK for a lengthened chamber. That in fact is probably not the major consideration on most guns, but rather the increased stress of regular use with heavier loads than they were designed for. It has been reported here on this forum on several occasaions that "Factory" gunsmiths routinely opened the chambers on Foxes sent back for re-work to 2 3/4". It is also noted that the factories when they changed from the shorter shells as standard often went to the longer chambers with no other modidifications or "Beefing UP" of their guns, they just cut them with longer chambers.
