William Powell Country

Lock, Stock and Barrel Series


Article written by 30 May 2012

Proof Positive

What is Proof? Is it necessary? How long has Proof testing been carried out?  How is my gun proof tested and by whom? All questions many of us ask and in truth few know the answer to.

Let us blow the cobwebs off the gun proofing mystery:

Proof is the testing of all weapons up to a two-inch diameter and two completely independent Proof Houses carry it out. One in London run by The Worshipful Company of Gunmakers, which was established by Royal Charter, by King Charles I, in 1637 and the other in Birmingham which was established by Act of Parliament in 1813, much against the will of the London Gunmakers.

Proof testing was borne out of guns blowing up in use whether it be for sport or for military purposes. The London Proof Houses Royal Charter in 1637 was to set up The Gunmakers Company and in the charter King Charles I selected 62 Gunmakers, Freemen of the City, to form the Company and he appointed a ‘Master’ and two Wardens to run the business which would include the rights of search, view, gauge, proof, trial and the marking of all hand held guns, great and small in London or it’s suburbs within a 10 mile radius.

The Birmingham Proof House was established at the insistence of the Birmingham Gunmakers who had been making arms in the city since approximately 1635 and for the Royal Ordinance since 1690. Following on from the successful opposition to the Parliamentary Bill raised by the London Gunmakers in 1813, which sought to force Gunmakers to mark their names and the town of manufacture on their arms, the same group of Birmingham Gunmakers held a meeting of the Birmingham Guntrade on 1st. April (Quite apt being April Fool’s Day !) 1813. The outcome of this meeting was that a committee was formed to obtain an Act of Parliament to create a Proof House in Birmingham. However, in order to secure sufficient funds to promote a private members Bill and to create the Birmingham Proof House together with adequate funds to acquire the land to build such a premises, shares were issued to fellow manufacturers within the Birmingham trade. The Act was passed later that same year and the Birmingham Proof House was built and was up and running within a few months of that date !

How is a gun proof tested?

The gun is submitted to either Proof House and a declaration has to be completed giving the gun’s make, serial number, calibre and chamber size and the proof required i.e. Standard, Superior or Steel Shot Proof for a shotgun – in the case of a rifled arm the make, serial number and calibre. In simple terms the weapon(s) are then checked to ensure that they are in a fit state for Proof or Reproof i.e. that they are tight on the action, head space is checked as are the barrels for dents, bulges, rivelling or pitting and if all is satisfactory they are then loaded with overcharged ammunition and after a thorough examination they are fired, cleaned and then” viewed” again. The Proof inspectors are looking for any faults or weakness within the barrels and action of the gun, e.g. dents, rivelling or bulging of the barrels and whether the gun is still ‘on the face’ i.e. there must not have been any movement of the action away from the barrel face on a shotgun or away from the bolt head in the case of a rifle after firing. A space of up to .002 of an inch is the maximum permitted.

All Proof ammunition, for use by both Proof Houses, is loaded at the Birmingham Proof House Laboratory, which is a highly sophisticated operation and carries an ISO 9001 accreditation and is currently upgrading this accreditation to EN ISO/IEC 17025. Every round of ammunition loaded is logged hence traceable, with records kept of every weapon proofed and the ammunition used. All ammunition is batch checked for pressure, velocity and momentum and again records kept for any possible future reference.

IN 1982 the U.K. government applied for, were accepted and signed up to become a member state of “The Permanent International Commission” for firearms testing known as C.I.P. This organisation was first founded in 1914 by Mr Joseph Fraikin the Director of the Belgium Proof House in Liege. In 1969 a Convention of 13 countries signed, had ratified and was  converted into law in each and every member state, hence the current C.I.P was borne. The current members of C.I.P. are:


Each C.I.P member state have a reciprocal agreement and acceptance of each others proof marks, systems and processes hence weapons imported into the U.K. from any other C.I.P. member state do not need to be reproof tested by our Proof Houses. However, all other countries exporting to a C.I.P. member state will have to have their weapons proof tested before being offered for sale, loaned or even to be pawned ! Every weapon imported into the U.K. from the U.S.A. has to be submitted to British Proof and if acceptable and they pass our Proof, then they will have our proof marks applied to their barrels and action.

Proof is the best method known to protect us, the shooter, whether in our sporting shotguns and rifles or for our Armed Services in our military weapons up to a two-inch bore. The Birmingham Proof House motto roughly translated from the Latin means “Safety for all”.

I believe therefore that Proof is a Positive Force in our shooting world and it is there to protect us all.

If I can answer any queries or questions please feel free to e-mail me directly at our Banbury headquarters : peter@williampowell.com

Peter Powell

I am the fifth generation of the William Powell Gunmaking Company which was founded by my great, great Grandfather in 1802. I started with the firm in 1968. I have been on the board of The Birmingham Gun Barrel Proof House since 1974, bei.. Read more.

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