Proof testing of rifles and/or
suppressors in the United Kingdom - legal and technical
A. Summary and
A. Summary and
- In the absence of any court decision to the
contrary, we are advised that a suppressor or sound
moderator, which is a freely removable accessory, designed
to be interchangeable between weapons
of different types and calibres, ought not to be considered to
be a "part of
a Small Arm". Such an accessory is not liable to fall
within the definition of a "Barrel" in the Gun
Barrel Proof Act 1868. We note, however, that the English
proof houses have expressed a different opinion which is consistent
with their own interests as private companies.
- Whether or not a suppressor is really a "Barrel" for
the purposes of the Proof Acts, there can be no legal requirement to submit any
"Barrel" for proof unless and until it is fitted to a
Small Arm which is to be sold, exchanged or exported, etc. There
is no offence in the Acts of selling an unproved "Barrel" on
- Similarly, there can be no UK legal requirement to submit
muzzle-threaded rifles for re-proof unless/until the
entire rifle is to be sold, exchanged or exported.
- In view of the wide range of firearm types and calibres
(even air guns) to which reflex suppressors
can be fitted, submitting bare suppressors for proof before
sale would not be practical.
- Reflex suppressors
are produced in a CIP country by
Europe's largest manufacturer of high-power rifle
- Noting that non-CIP countries like Switzerland and the
USA manage very well without compulsory proof, we conclude
that CIP proof is no substitute for modern workshop quality assurance procedures.
- Although a number of suppressors have been proof-marked
by the London Proof House for calibres larger than the
baffle hole diameter, we warrant that firing an appropriate CIP proof
cartridge through a correctly-fitted reflex suppressor will
not harm it
in any way.
- In principle, we neither recommend nor advise against
the proof testing of rifles after they have been fitted with reflex suppressors.
- In the past, some perfectly good rifles have destroyed due to incorrect proof loads or
other errors. Other rifles have suffered the sort of
minor or latent damage which is to be expected when a
vital component (the cartridge case) is subjected to
an unknown pressure at or above its yield stress. Subject
to our warranty given in point 7. above, any proof or
re-proof is carried out at the owner's risk, particularly
with regard to any possible loss or damage to the rifle.
On 31 August 2000, the London and Birmingham Proof Houses
issued a circular entitled "Screw cutting of rifle
muzzles and the fitting of sound moderators and other
items". A further circular entitled "Conversion of
Barrels and the Fitting of Muzzle Accessories" was issued
by the Proof Houses in October 2001.
The contents and inferences of these circulars have been hotly disputed by the gun
trade, and we consider that they are misleading to the extent
that they convey the impressions:
(a) that there may be a legal requirement to submit all sound
moderators for proof and,
(b) that there may be a legal requirement to submit all rifles for
proof or re-proof after the cutting of an external screw
thread at the muzzle.
Section 122.(3) of the Gun Barrel Proof Act 1868 ("the
1868 Act") creates an offence of selling or exchanging,
or attempting to sell or exchange, a Small Arm the Barrel or
Barrels of which are not duly proved or marked as proved.
However, the terms "Small Arm" and "Barrel" are
separately and distinctly defined in the Act and from these definitions it
is clear that
there is no offence of selling, etc. an unproved "Barrel" on its
own. Therefore, even if sound moderators were deemed to be
"Barrels" as defined by the 1868 Act (a suggestion
which is hotly disputed), there is no legal requirement to
have them proved unless they are sold as part of a "Small
Similarly, with regard to the cutting of a screw thread on
a rifle muzzle (or for that matter any other repair,
replacement or modification of a Barrel), there can be no offence committed unless or until the entire
Small Arm is
subsequently offered for sale, exchange, export etc. Even
if/when this were to happen, the requirement to submit a
barrel for re-proof only arises if the barrel has been "unduly
reduced in Substance or Strength".
As professional engineers, we reject any suggestion that a threaded
rifle muzzle with a factor of safety against failure of more than
four (as in the
extreme case of a 1/2" UNF thread on a typical 7.62 mm rifle)
is "unduly reduced in Substance or
Strength", just as similar suggestions were dismissed in
written evidence for the case of Regina v Beatham (see R-v-Beatham_evidence.pdf
- 986 kB Adobe Acrobat file). We note that on receipt of this evidence, the
Crown abandoned its case and the Defendant was duly discharged with
his costs awarded from the public purse.