"your CIP standards versus our Colonial SAAMI standard reflect that."
Is there any evidence that SAAMI standards sanction the use of 2 3/4 shells in 2 1/2 inch chambers? I recall pressure standards per gauge in PSI given by SAAME but no length recommendations.
CIP technical data is more extensive. The testing of cartridges follows a statistical model which arrives at a recommended AVERAGE pressure from a test run. Individual shells in the run can run substantially ABOVE the average, ie 740 bar max pressure allowed for 12 gauge non-magnum can have some shells exceeding 800 bar.
So in a box of 25 there may be some shells that produce higher pressure. Add to that the increase from a longer hull constricting the shot passage in the forcing cone and you create an UNNECESSARY RISK.
Bottom line from makers, CIP, proof houses, gunsmiths (and possibly SAAMI pending evidence), is do not fire longer shells than the chamber nominal length.
