Originally Posted By: Jim Legg
Hi Larry,
You were doing fine until you got to the forcing cones. Forcing cones have an effect on recoil because________________________?


Because Burrard and Thomas say so, Jim--Burrard indirectly, Thomas (and others) more directly?

Burrard says: "If the mouth of the cartridge is compressed by being held by the chamber cone, the resistance to the initial movement of the shot charge will be greater and the pressure will be increased." What happens to the increased pressure? If you increase the pressure without changing anything else, won't you also increase velocity--which increases recoil?

Thomas: "Again, the prevalent use of 2 3/4" cases, suitably loaded, for guns with 2 1/2" chambers may be perfectly satisfactory if the guns have normal cones, but not if the cones are exceptionally abrupt, as some are, when the use of the longer case may give rise to objectionable, or at least enhanced, pressures." He refers to a specific case: "This gun shoots the Impax cartridge, with its 2 1/2" case, very satisfactorily. But with cartridges with 2 3/4" cases, though designed for 2 1/2" chambers, it recoils unduly and makes his right arm numb. Three out of four crimps were shot right off . . . " Gun writer Charles Fergus reported precisely the same problem when shooting British shells in longer hulls (but designed for 2 1/2" chambered guns) in a pre-1900 Brit double: Significant increase in recoil, blown ends. No problems with true 2 1/2" cases. And no problems with either shell in a Brit gun from the 1930's, with 2 1/2" chambers but longer forcing cones. The excessive restriction caused by the design of the forcing cone certainly appears to be the culprit. That's why we can't really say that 2 3/4" shells, even if loaded to proper pressures, are a good choice in ALL 2 1/2" guns. If you're getting significantly increased recoil and blowing the ends off shells, you probably ought to stop.