Bore for weapons

A cartridge in a weapon capable of firing several different calibers is provided. The cartridge bore is adapted for use in weapons having extractor and positioner mechanisms which permit use of different caliber casings in the same weapon. With the cartridge bore according to the present invention, casings are more easily removed after firing and are less likely to stick.

BACKGROUND OF INVENTION 
1. Field of Invention 
The present invention relates to weapons, more particularly to cartridge 
bores for weapons adapted to fire different calibers. 
2. Description of Prior Art 
U.S. Pat. Nos. 4,543,741 and 5,341,587 of which Applicant is inventor, 
provided ejector and cartridge positioner mechanisms which permit weapons 
to fire any of several different caliber cartridges. The ejector and 
positioner mechanisms of these types provided structure for engaging the 
rear portion of cartridges to enhance the positioning and extraction 
functions. These types of mechanisms provided structure for proper seating 
both rimmed and rimless cartridges in the rear of weapon cylinders, while 
also making the cartridges more easy to load. 
Problems existed, however, with forward portions of the cartridges in 
weapons of this type. It was typical to provide stepped surfaces along the 
interior cylinder walls to allow proper acceptance and seating of the 
cartridges. With stepped cylinder walls, the cartridge casing material, 
which was typically of brass, would be forced against the step surfaces 
during use as the weapon was fired. If pressures were sufficiently high, 
the brass material could even flow to some extent. Thus, in certain 
instances the cartridge casing might tend to stick or resist extraction 
after firing. The cartridge could be removed relatively easily, but 
extraction and reloading times would be considerably slowed. 
Portions of the cartridge case in some instances after use in stepped 
cylinders would enlarge. The enlargement could be to such an extent due to 
high pressure flow that the cartridge case became unsuitable for further 
reloading. In some additional cases with step surfaces in the cylinder 
walls, the cartridge case could shear or split or burst as a result of 
high pressure flow. 
SUMMARY OF INVENTION 
Briefly, the present invention provides a new and improved cartridge bore 
structure for a firearm. The cartridge bore structure of the present 
invention is provided in a weapon having an ejector and cartridge 
positioner mechanism capable of firing different calibers of cartridges 
from the weapon. An improved cartridge bore formed in the weapon according 
to the present invention includes a rim seating portion for seating 
cartridges having rims. The rim seating portion has a length along a 
longitudinal axis of said cartridge bore which is equal to the thickness 
of the widest cartridge rim of a cartridge to be fired from the weapon. 
The rim seating portion also has a cylindrical surface with an inner 
diameter larger than the outer diameter of the largest cartridge rim to be 
fired from the weapon. The cartridge bore structure according to the 
present invention also includes a first taper segment inwardly of the rim 
seating portion. The first taper segment forms an outer wall of the 
cartridge bore extending inwardly along its longitudinal axis. The first 
taper segments extends inwardly from the rim seating portion a distance 
substantially equal to the length of the longest cartridge to be fired 
from the weapon. The first taper segment outer wall also has an inner 
diameter at a rear portion adjacent the rim seating portion substantially 
equal to the largest cartridge casing cylinder to be fired from the 
weapon. According to the present invention, the first tapers segment outer 
wall taper inwardly along the distance of its inner extent about one 
percent per unit length. 
Inwardly from the first taper segment, the cartridge bore structure 
includes a second taper segment. The second taper segment forms an outer 
wall of the cartridge bore extending inwardly from said first taper 
segment to a forward end of the cartridge bore. The second taper segment 
has an inner diameter at a rear portion at a juncture with the first taper 
segment which equals or matches the diameter of the first taper segment at 
such juncture. With the present invention, the second taper segment outer 
wall tapers inwardly along its inner extent about five percent per unit 
length. 
According to the present invention, it has been found that a cartridge bore 
structure so formed permits firing of several different calibers of 
cartridge in the same weapon. This can be done while reducing the tendency 
of the cartridge casings to stick and also making removal of the casings 
after firing more easy to perform.

DESCRIPTION OF PREFERRED EMBODIMENT 
In the drawings, a revolver cylinder body B according to the prior art 
(FIG. 1) is shown. The prior art revolver cylinder body B has a cartridge 
or casing ejector/cartridge positioner mechanism M fitted therein. The 
mechanism M, for example, may be of the type shown in U.S. Pat. No. 
5,341,587 of which applicant is inventor. A cylinder body B of this type 
with the ejector/cartridge positioner mechanism M is capable of firing 
cartridges of different calibers, both rimmed and rimless, even from a 
single load of such cartridges into the cylinder body B. Reference is made 
to applicant's prior U.S. Pat. 5,341,587 and 4,543,741 for further details 
of the operation and structure of typical examples of such revolver 
cylinder bodies. 
In the revolver cylinder bodies of the prior art, it has been conventional 
practice to have one or more stepped surfaces one of which is shown in the 
drawings at reference numeral 10 (FIG. 2) at selected positions along the 
length of each revolver cylinder bore. The stepped surfaces 10 allow more 
close engagement with and accommodate cartridges or casings of various 
diameters. Typically, the stepped surface or surfaces 10 are located at 
positions along the length of the revolver cylinder bore 11. The example 
stepped surface 10 is shown in FIG. 2 in somewhat enlarged scale between a 
first cylinder bore wall portion 12 of a first inner diameter along its 
length and a second cylinder bore wall portion 14 of another, smaller 
inner diameter along its length. 
There were several problems with revolver cylinder bores with stepped 
surfaces 10 of this type. If several of such stepped surfaces were to be 
provided in a cylinder bore for each of several calibers, manufacturing 
costs and complexity for this type of revolver cylinder body were greatly 
increased. If stepped surfaces were provided for only certain calibers to 
reduce costs and complexity, the adaptability and versatility of the 
weapon for use with a variety of casing or cartridge sizes was 
significantly reduced. 
Further, even if only one set of stepped surfaces, as that exemplified at 
10, was provided in the revolver cylinder body B, problems resulting from 
casing material flow were present as has been detailed above. These 
problems included extraction or unloading problems, reloading problems and 
even possible problems of casing rupture or breakage in certain 
situations. 
With the present invention, a new and improved cartridge bore structure S 
(FIGS. 3 & 4) for a firearm is provided. The cartridge bore structure S of 
the present invention is provided in a body portion 20 of weapon having an 
ejector and cartridge positioner mechanism capable of firing different 
calibers of cartridges from the weapon. It should be understood that the 
weapon may also be some other type of a firearm, which may be another form 
of revolver cylinder body, a carbine, an automatic pistol or the like, 
capable of firing different calibers of cartridges. 
An improved cartridge bore structure S formed in the weapon according to 
the present invention includes a rim seating portion 22 for seating 
cartridges having rims. The rim seating portion 22 has a length 24 along a 
longitudinal axis, indicated by an arrow 26, of the cartridge bore 
structure S which is equal to the thickness of the widest cartridge rim of 
a cartridge to be fired from the weapon. The rim seating portion 22 also 
has a cylindrical surface 28 with an inner diameter larger than the outer 
diameter of the largest cartridge rim to be fired from the weapon. 
The cartridge bore structure S according to the present invention also 
includes a first taper segment 30 inwardly of the rim seating portion 22. 
The first taper segment 30 forms an outer wall of the cartridge bore S 
extending inwardly along its longitudinal axis 26. The first taper segment 
30 extends inwardly from the rim seating portion 22 a distance as 
indicated at 32 substantially equal to the length of the longest cartridge 
to be fired from the weapon. The outer wall of the first taper segment 30 
also has an inner diameter at a rear portion 34 adjacent the rim seating 
portion 22 substantially equal to the largest cartridge casing cylinder to 
be fired from the weapon. According to the present invention, the first 
taper segment outer wall taper S inwardly along the distance of its inner 
extent about one percent per unit length. 
Thus, for example, a cartridge bore structure formed in a revolver capable 
of firing different caliber shells would have a rim seating portion 22 
having a nominal inner diameter of 0.44" and a nominal length of 0.06". 
The inner diameter of the first taper segment 30 at its rear portion 34 
adjacent the rim seating portion 22 measures a nominal 0.393". 
Inwardly from the first taper segment 30, the cartridge bore structure S 
includes a second taper segment 38. The second taper segment 38 forms an 
outer wall of the cartridge bore S extending inwardly from the first taper 
segment to a forward end 40 of the cartridge bore S. The second taper 
segment 38 has an inner diameter at a rear portion 42 at a juncture 44 
with a forward portion 46 of the first taper segment 30 which equals or 
matches the diameter of the first taper segment 30 at such juncture. With 
the present invention, the second taper segment outer wall tapers inwardly 
along its inner extent about five percent per unit length. Accordingly, 
for a cartridge bore structure first taper 30 having a segment rear 
portion 34 with an inner diameter of 0.393", the juncture 44 of its 
forward portion 46 with the second taper segment 38 is located 1.25" 
inwardly from the rear portion 34. At the juncture 44, the forward portion 
46 has a nominal inner diameter of 0.381". The taper of the first taper 
segment 20 is thus a nominal 0.012"/1.25" or about one percent (1%) per 
unit length. Manufacturing tolerances typically allow some minor variation 
of .+-.0.006" in the inner diameters of the taper segment 20 between rear 
portion 34 and forward portion 46. 
The second taper segment 38 has a like inner diameter of 0.381" at the 
juncture 44 with first taper segment 20. The second taper segment 38 
extends inwardly along the longitudinal axis 26 for a distance of 0.443" 
to the forward end 40 of the cartridge bore structure S. At the forward 
end 40, the second taper segment 30 has an inner diameter of 0.359". The 
taper of the second taper segment 30 is thus a nominal 0.022"/0.443" or 
five percent (5%) per unit length. Manufacturing tolerances typically 
allow some minor variation of .+-.0.003" in the taper of second segment 30 
between the juncture 44 and the forward end 40. 
According to the present invention, it has been found that a cartridge bore 
structure S so formed permits firing of several different calibers of 
cartridge in the same weapon with high accuracy. This can be done while 
reducing the tendency of the cartridge casings to stick and also making 
removal of the casings after firing more easy to perform. The cartridge 
casings are better adapted for subsequent reloading use. Potential rupture 
hazards are also reduced. 
Having described the invention above, various modifications of the 
techniques, procedures, material and equipment will be apparent to those 
in the art. It is intended that all such variations within the scope and 
spirit of the appended claims be embraced thereby.