Improvements in the Construction of Breech Bolts, and in the Method of Fitting the same to Breech-loading Fire Arms.
Year: 1891

page_text: Date of Application, 25th Nov., 1891-Accepted, 2nd Jan., 1892
COMPLETE SPECIFICATION.
Improvements in the Construction of Breech Bolts, and in the
Method of Fitting the same to Breech-loading Fire Arms.
I, KAREL KRNKA, of Vinohrady, Pragne, Bohemia, in the Empire of Austria,
do hereby declare the nature of iny said invention and in what manner the same
is to be performed, to be particularly described and ascertained in and by the
following statement :-
The object of my invention is to effect improvements in the breech bolts of
breech-loading fire arms, my improvements being more particularly applicable to
small fire arms.
And in order that my said invention may be particularly described and ascer-
tained, reference is hereby made to the accompanying drawings, in which similar
letters of reference indicate corresponding parts.
Fig. 1 is a longitudinal section, showing the position of the mechanism, when
locked.
Fig. 2 is a similar section, showing the mechanism unlocked, and the breech
bolt A partially withdrawn.
Fig. 3 is an elevation of a portion of the breech bolt A. with the head B in.
position when unlocked.
Fig. 4 is a front view of the same.
Fig. 5 is a similar elevation of the breech bolt A with the head Bin a locked
position.
Fig. 6 is a front view of Fig. 5.
Fig. 7 is a back view of the locking ring C..
Fig. 8 is a front view, and Fig. 9 is a section, on the line xx, of the same
ring.
Fig. 10 is a back view of the fixed ring D.
Fig. 11 is a front view, and Fig. 12 is a section, on the line y y, of the same
ring.
a a are two studs formed in one with the breech-bolt A. B is the head of the
breech bolt, formed separately, the form of the head being shown in Figs. 3, 4, 5
and 6.
The stem of the head fits the bore of the breech-bolt, as shown by dotted
lines in Figs. 3 and 5. The outer end of the head is of larger diameter than the
stem, and has two studs formed in one therewith. The head is held in the
breech-bolt by two studs b which engage in an internal annular groove a', forming
a modified form of bayonet joint. The head B is inserted in the breech-bolt, when
in the position shown in Fig. 6, the studs gaining access to the groove a¹ by
passing through slots in the bore of the breech-bolt.
The ring D is fixed in the breech E, by screws or otherwise, close up to the
barrel F, and does not rotate. dd are two slots formed in the ring D, to admit
the studs of the head b. d d are two helical inclines. The ring C has two
slots cc to receive the studs a a after the studs bb have passed through to the
ring D. are two short inclines formed on the mutilated collar c² of the ring C.
ele are the sides of the slots formed in the breech to guide the studs a and b, on
their way to the rings C and D. ee are short inclines formed in the grooves e',
one on the left wall below, and the other on the right wall above the bolt A.
In order to lock the bolt it is turned, by any suitable means, from left to right.
The rotation of the bolt causes the studs a a to impinge upon the inclined surfaces e,
and thereby start the bolt forward. The continued turning of the plug causes the
edges of the studs a a to slip upon the helical surfaces d' d', leaving their previous
position behind the studs bb. The helical surfaces c¹ c', on the ring C, then drive

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forward the studs bb, and therewith the head B; the ring C being turned by the
studs a, whereby the bolt is locked, as shown in Fig. 1.
In order to unlock the bolt, it is turned by any suitable means from right to
left. This motion is continued until the studs a a, by impinging upon the helical
surfaces d' d¹, are driven backwards together with the bolt A and head B. The
cartridge case is thereby loosened before the bolt is completely opened. The bolt
can then be withdrawn to the position shown in Fig. 2:
I do not confine myself to the precise arrangement of parts herein before
described, as obvious modifications may be made in the same without departing
from the nature of my invention.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
:-
1. In fire arms fitted with breech-bolts, the combination of the locking-bolt. A
and head B, formed with studs a and b, each capable of being rotated on its centre,
and placed in a suitable position for sustaining the retroaction arising from the
firing of the arm, substantially as and for the purposes herein before described and
illustrated by the drawings.
2. In fire arms fitted with breech-bolts, the combination of the locking-bolt A
and head B, carrying studs a and b, each capable of being, rotated on its centre,
and placed in a suitable position for sustaining the retroaction arising from the
firing of the arm, the ring C, with or without helical surfaces c', forming fixed or
movable fulcruins for the locking studs, substantially as and for the purposes herein
before described and illustrated by the drawings.
3. In fire-arms fitted with breech-bolts, the combination of the locking-bolt A
and head B, studs a and b, ring C, with or without helical surfaces c', a fixed or
movable ring D, with or without helical surfaces d', substantially as and for the
purposes herein before described and illustrated by the drawings.
4. In fire arms fitted with breech-bolts, the combination with the locking-bolt A
and head B, studs a and b, ring C, with or without helical surfaces c', fixed
ring D, with or without helical surfaces d', formed in one with the barrel F,
substantially as and for the purposes. herein before described and illustrated by the
drawings.
5. The general construction, arrangement, and combination of the several and
respective parts, together forming my improvements in the construction of breech-
bolts, and in the method of fitting the same to breech-loading fire-arms, substantially
as herein before described and illustrated by the drawings.
Dated 25th November 1891.
GEO.
DOWNING,
8, Quality Court, London, W.C., Agent.