Some years ago, I acquired a box of 3in Winchester cartridges, which are still in good condition. They are the Winchester Power Piston Magnum, loaded with 1.7⁄8oz of BB shot.

Are they safe to use with this gun?

Bill Harriman
One of the basic principles of the CIP international proof system is that any CIP-tested cartridge is safe to use in a gun, which has been tested in the proof house of a CIP country, provided that it is used in a chamber of the same length as the cartridge.

If you look on the box of Winchester cartridges, you will be able to see if they have been CIP-approved; there will be a little mark of a crown over a rose over the letter B in Birmingham or L in London.

The shotgun will have passed through Winchester?s own proof facility for testing.

However, this is not recognised by the UK proof authorities and the gun must be re-proofed on import to the UK at one of the two proof houses.

It may well have been proofed in another European proof house, such as in Germany or Belgium, so it is likely that it bears CIP proof marks.

If the gun has CIP proof marks and the cartridges are CIP-tested, then it is safe to use them.

If you are unsure, go to a competent gunsmith or contact the Birmingham Proof House and speak to a member of its technical staff on 0121 643 6860.