Regarding the case length of 2 1/2" shells loaded to pressures deemed safe for guns proved to a service pressure of 3 tons per square inch, all meet the pressure safety requirements of proof.

However, choose the actual shell depending on the forcing cone dimensions of a given gun. Those with steep forcing cones will be better suited to 65mm cases than 67mm or 67.5mm cases, even though the pressures are the same.

This is because the opened case will partially narrow the cone urther and prouce greater pressure. It is a matter of common sense that if your cases are ragged at the ends after firing, they are too long and you should use shorter ones.

I'm glad we all now seem to be in agreement that it is not safe to put factory loaded 70mm shells in a 2 1/2" proofed and chambered gun.

If your re-loads are opening out in the gun you are using and not showing any fraying, then they must be opening fully in the chamber and are likely not a problem. If they are fraying, then you need to use shorter cases or lengthen your chamber - which, of course requires the gun to be re-proofed.


Last edited by Small Bore; 04/09/07 09:21 AM.
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