​Reproof, or the further test of a gun after its original proof, may be necessary for a variety of reasons, of which the main ones are:

  • Indications of weakness in action or barrel, including cracks, pitting, bulges, dents or failure of the brazing of the lump.
  • Potential weakening, such as by conversion to ejector, repair of the action or barrel by welding, electrolytic deposit of hard chrome or other metal in the barrel.
  • Enlargement of the internal diameter of the barrel, or lengthening of the chamber so that it no longer conforms with the existing proof marks.
  • Replacement of action, barrel, barrel lug or extension.
  • Fitting of any attachment, such as a variable choke, which must withstand the pressure of firing.
  • Present inadequacy of earlier proof. Black powder proved guns, most commonly proved over 90 years ago, may not be safe for use with smokeless cartridges and require reproof for nitro powders.


If mishandled or neglected, a gun may be damaged or weakened, even in a short period of service. In such circumstances work necessary to return it to serviceable condition, may render invalid the original proof marks.

Indications of weakness may only be apparent to those trained to recognise them. For that reason, inspection of guns by a gunmaker, at regular intervals, is recommended, and advice to submit for reproof should be followed without delay to avoid undue risk of personal injury.

Guns are submitted to reproof at the owner's risk and the gunmaker is entitled to payment for his work, regardless of the result of proof. Guns will not be accepted for reproof, if it is the decision of the gunmaker that they are not in a fit condition to be proved.