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Reasons for Gun Barrel Proof |
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Gun Barrel Proof, or proof testing of firearms and the ammunition that is used in them is compulsory in the UK. It was brought about by reputable gun makers in order to establish the safety and integrity of the firearms concerned, thus giving protection to the user and establishing a quality standard.
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British Proof Law as represented by the Gun Barrel Proof Acts of 1868, 1950 and 1978. The "Rules of Proof" are defined under the authority of these Acts. The "Rules of Proof 1954 & 1978" can be purchased from either of the London or Birmingham Proof Houses. The 1954 rules, which were originally approved by the then Ministry of Supply, came into effect on 1st February 1955 and xx dd ???? for the 1978 act, however Proof under the earlier Rules of 1875, 1887, 1896, 1904, 1916 and 1925 remains valid provided the weapon still conforms with the Proof Marks of the time in terms of dimensions of the bore, load, nature of propellant, and has not been materially altered in any vital aspect including such as chamber length, re-sleeving, chromium plating or any other form of metal deposition in the bore.
The "Rules of Proof" derive their authority from the Proof Act. They apply to all Small Arms, within certain limits of bore size and projectile weight, but do not include weapons made for the use of HM Forces. Proof Testing of these military weapons falls under the jurisdiction of the Directorate of Inspection of Arms who use their own Proof Marks.
The "Rules of Proof" do not apply to air weapons or other guns that do not use an explosive propellant cartridge.
Types of Proof fall into three divisions:-
(a) Provisional Proof.
(b) Definitive Proof.
(c) Special Definitive Proof.
Provisional Proof... This is mainly for the convenience of the gun trade. It is applied only to shot gun barrels and is intended to weed out non obvious faults and prevent the maker from wasting time and effort on a tube that is faulty. The gunmaker submits his tubes to the Proof House which deals with them in a manner described on the Proof Methods page. If they are satisfactory they are returned for the work to be continued.
Definitive Proof... All weapons must undergo this, either in the "white" or when fully finished.
Special Definitive Proof... This applies to weapons that are intended to be used with loads that develop pressures greater than the normal service loads expected with this type of weapon. This can be done either as the compulsory proof of a weapon that is deliberately designed for heavier than usual loads or as a result of a person wishing to use a heavier load in a weapon that was not originally proved to that standard.
Re-Proof is required after a gun has been proofed and used, but a change in condition or dimension may cause re-proof to be required. The most common causes of this are:-
Increase in bore size or chamber length that causes the original proof to be invalidated.
Enlargement of bore diameter in removal of pitting weakens barrels and is the most common cause of barrels becoming out of proof.
Physical signs of failure or possible failure such as pitting of the barrel, cracking or bulging.
Replacement of the barrel, re-sleeving, welding brazing or electrolytic deposition of any form including chromium or Nickel plating.
Fitting a device such as a muzzle brake, if a rifle or a variable choke if a shot gun.
Use of a propellant or load which produces a pressure in excess of that for which the firearm was designed. Particularly to the use of smokeless cartridges in a gun designed and proofed for black powder only.
Originated... 18 December 2002, New Domain... 13 February 2004, Upgraded... 26 January 2007,
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