It is noted that immediately after the introduction of the fold crimp shell in Great Britian there was concern the nominal 2½" (in reality about 2 9/16") shell was so short it would be mistaken for a 2" one. Tests were begun immediately upon putting the normal load uo in a fold crimped 2 3/4" hull which resulted in a shell having about the same identical "Loaded" length. Results all appeared positive & this work was completed very shortly following WWII. These tests were conducted by the British Ammunition makers who had the knowledge & equipment to fully test. This was fully reported on by Burrard in "The Modern Shotgun". These tests were conducted using "Thick Paper" hulls in standard chambers with standard forcing cones. The conclusion was as long as there was clearance between the end of the loaded shell & cone for the crimp to start to open in a normal manner & the load was suitable for the gun there was little concern about the lapping of the fired hull into the cone. I do believe that virtually all British shells from that day to this marked for use in 2½" chambers & which are closed with a fold crimp have been longer than the chamber in which they were to be fired. Work in this field later than the 1940's have simply been a re-invention of the wheel. It would not of course be recommended to fire a shell longer than the chamber in a gun having a "Stepped chamber in which the crimp would actually open up into the bore itself or a shell long enough to actually have the crimped end squeezed into the cone prior to firing. This gives the effect of an overly strong crimp. Along this line it was "Not" recommended to fire 2 3/4" Roll Crimp shells in the shorter chamber, only the fold crimp ones. Roll crimped 12ga 2 3/4" shells were available well back into the 1800's. Many American 12ga doubles were ordered with 2 3/4" chambering & according to Hunter Arms Drawings they were standard on their 12ga guns at least as early as 1907. Several of my Lefever 12's have 2 3/4" chambers which I have no reason to believe are not original & I have both a 10ga & a 16ga with 3" chambers. Shells for both these gauges were available in 3" length when the guns were built, but never became standard in either & became increasingly harder to find as time went on. There is "Absolutely No" reason to believe either of these are a later re-chambering.
