Proof Law

​The present law on the subject is to be found in the Gun Barrel Proof Acts 1868, 1950 and 1978 and various Rules of Proof, but particularly those of 1925, 1954, 1986 and 1989, when the metric system of measurement was introduced. Copies of the several Acts and of Rules of Proof of 1989 may be obtained from either Proof House, details of which appear at the end of these particular pages. The maximum prices per barrel, which may be charged for proof, are set down in the Gun Barrel Proof Act of 1950 and subsequent statutory orders.

The Proof Acts

The provisions of the Acts apply to all small arms, whether of present use or future invention, within certain fixed limits of bore size and projectile weight (with the exception of some military arms made for the use of H. M. Forces). Air guns, not being "firearms", are specifically excluded.

The Proof Acts lay down that no small arm may be sold, exchanged or exported, exposed or kept for sale or exchange or pawned unless and until it has been fully proved and duly marked. The maximum penalty is £1,000 for each offence, but with provision for higher penalties where, for instance, the sale of a number of guns constitutes one offence. Alteration to or the forging of proof marks is a still more serious offence.

Arms previously proved and bearing apparently valid proof marks are deemed unproved if the barrels have been enlarged in the bore beyond certain defined limits or, if the barrel or action has been materially weakened in other respect.

The offence of dealing in unproved arms is committed by the seller and not by any unwitting purchaser.


The importation of unproved arms into the United Kingdom is subject to control as prescribed in Section 122(4) of the 1868 Act, as amended by the Act of 1978.

Notification of importation has to be given to the Proof House within seven days and/or the arms submitted to proof within twenty eight days of arrival in this country.

These regulations do not apply to small arms imported by any person for his own personal use, while they remain his own property. Penalties for offences are similar to those for the sale of unproved arms.