Design - Page 2
An
alternative design to the Greener 'cross bolt' or Westley Richards Dolls
Head was the
Webley Screw Grip top extension
patented by T. W. Webley and T. Brain (P. Webley & Son) under patent No: 3053 in
1882.
The design made use of either the
more ornate and
complex
Dolls
Head type or a straight or blade type extension. The later dispensed with the
Dolls head leaving a simpler straight slot cut in the top edge of the
standing breech.
Although the blade design would have been less expensive to produce the Dolls
head variant seems to have been the preference of W R Leeson.
The design is based on an external screw or thread
mounted on the vertical spindle of the top lever inside the standing breech. On the upper part of the
spindle, inside the standing breech is also a cam mechanism. When the top lever
is operated to open the breech, the screw mechanism rotates inside the spindle
assembly and places an upward lifting force on the underside of the top
extension. In effect its acts as an assistance to the opening
of the breech. When the breech is closed, as the sliding bolts lock
into the barrel lumps, the top cam mechanism places a downward force on a
stepped lug forming part of top
extension. This has the effect of pushing the top extension,
whether of the Dolls Head or indeed the Blade Head extension design down into the
slot on the upper face of the standing breech. Once home, both the sliding bolts
lock into position in the cut outs of the barrel lumps and the third bite
mechanism locks home the top extension, ensuring a very strong bolting.
The Webley screw grip satisfies both aspects
concerning breech burst and breech/barrel flexing. Barrel flex is overcome when
the head itself is located into the slot cut in the standing breech of the action, the
barrel being held secure between the fences, as can be seen in the picture above.
The second feature
is to lock the breech closed in combination with the
sliding bolts. This was achieved by a modification to the top lever spindle
incorporating a screw thread or cam type mechanism. When the breech was closed
the spring mechanism of the top lever ensures the cam exerts
downward force on the top extension. The combination of the two design aspects
produced an exceptionally strong breech to action joint as well as an
aesthetically pleasing feature.
Today, it is generally accepted that the need for a third bite is
unnecessary providing quality gunmaking techniques and materials are employed.
As
discussed, during the Victorian era, makers could not be sure of the strength of
their actions, failure could spell great danger, even potential death to the
user and as a result of failure, commercial difficulty for the maker, in both legal
claims and a bad name. To this end, gunmakers aired on the side of caution,
Purdey for example developed their own third bite system under Patent 397
of 1878. This design incorporated a hidden extension which protrudes from the
barrel above the extractor mechanism. The concept was to still retain the
presence and hence strength of the third bite but one which was hidden from
view.
Hence the creation of the hidden third bite or hidden fastener as it is often
referred to in the USA.
The design requires
a slot to be formed in the vertical face of the standing breech but not so it
protrudes through the top surface of the action itself giving onlookers the impression that
the gun does not possess a third bite.
The mechanism functions in a similar manner as
the Webley Screw Grip, by producing a downward force on the top side of
the extension via a sprung loaded cam onto the shoulder of the
extension, ensuring total closure of the breech occurs. Perhaps not as elegant
solution as the Webley Screw Grip design but did provide the design with the
hidden "from view" element.
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