U.S. patent application number 09/963968 was filed with the patent office on 2002-03-28 for breech plug with primer pocket for converting a black powder gun to smokeless powder.
Invention is credited to Lewis, Gregory S..
Application Number | 20020035800 09/963968 |
Document ID | / |
Family ID | 27398725 |
Filed Date | 2002-03-28 |
United States Patent
Application |
20020035800 |
Kind Code |
A1 |
Lewis, Gregory S. |
March 28, 2002 |
Breech plug with primer pocket for converting a black powder gun to
smokeless powder
Abstract
The breech plug with primer pocket of the present invention
converts a black powder propellant muzzle-loading gun to a
smokeless powder propellant muzzle-loading gun by providing a close
fitting primer pocket wall, a flush fitting extractor that also
supports the primer's sides, and a primer pocket seat that is cut
at an angle of 25 degrees from the perpendicular of the primer
pocket wall to conform to the front face of the primer, such that
when the primer is seated against the primer pocket seat, a gas
seal is formed. A gas seal is also formed at the primer's side
walls.
Inventors: |
Lewis, Gregory S.;
(Heltonville, IN) |
Correspondence
Address: |
Clifford W. Browning
Woodard, Emhardt, Naughton, Moriarty & McNett
Bank One Center/Tower
111 Monument Circle, Suite 3700
Indianapolis
IN
46204
US
|
Family ID: |
27398725 |
Appl. No.: |
09/963968 |
Filed: |
September 26, 2001 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
60235493 |
Sep 26, 2000 |
|
|
|
60262944 |
Jan 19, 2001 |
|
|
|
Current U.S.
Class: |
42/51 |
Current CPC
Class: |
F41C 9/08 20130101 |
Class at
Publication: |
42/51 |
International
Class: |
F41C 007/00 |
Claims
I claim:
1. A breech plug with primer pocket for converting a black powder
propellant gun to smokeless powder propellants, comprising a
smokeless powder propellant breech plug sized to be closely
removably fit within the breech of a black powder propellant
muzzle-loading gun, with a breech opening at a first end of the
plug and a primer pocket at a second end of the plug with means to
pass smokeless powder propellant gas from the primer pocket to the
breech opening, wherein the primer pocket is substantially
cylindrical in shape with a diameter of about 0.2435 to about
0.2450 inches that is open at the first end of the plug and that
has a primer pocket seat at the opposite end in direct
communication with the means to pass smokeless powder propellant
from the primer pocket to the breech opening, the primer pocket
seat having means that conform the shape of the primer pocket seat
to the front face of a primer filled with smokeless powder
propellant to form a gas seal between the primer pocket seat and
the primer, and primer extractor means flushly fitted against the
primer pocket to support a primer wall and to eject a spent primer
from the primer pocket.
2. The breech plug with primer pocket of claim 1 wherein the primer
pocket and primer pocket seat was formed with a boring bar with a
lead angle of about 25 degree at the second end of the plug to a
depth of about 0.299 to about 0.306 inches.
3. The breech plug with primer pocket of claim 1 wherein the length
of the plug between the first and second ends is about 1.318 to
about 1.320 inches.
4. The breech plug with primer pocket of claim 1 wherein the plug
is removably fit within the breech of a black powder propellant
muzzle-loading gun with means to thread the plug into the gun's
barrel.
Description
[0001] This application claims the benefit of co-pending U.S.
Provisional Patent Application Ser. No. 60/235,493, filed Sep. 26,
2000, and Ser. No. 60/262,944, filed January 19, 2001.
[0002] The present invention relates generally to muzzle-loading
firearms, and more particularly to a new type of breech plug and
primer pocket that effectively seals the combustion chamber of a
muzzle-loading gun so that high pressure smokeless gas propellants
may be used due to the high pressure gas remaining inside the
combustion chamber, rather than being allowed to escape, such as
through the conventional flash hole of most conventional muzzle-
loaders.
BACKGROUND OF THE INVENTION
[0003] Although the THOMPSON-CENTER brand 209.times.0.50
muzzle-loading gun uses a shotgun shell primer, the walls of the
primer are not supported over all their surfaces by a close fitting
backing of steel in the gun's breech. Gas therefore escapes because
of the loose fit of the primer in the breech, and thus low gas
pressure black powder propellants, or their low gas pressure
substitutes, are all that can be safely handled in such guns due to
the relatively low gas pressure they require. The THOMPSON-CENTER
brand 209.times.0.50 muzzle-loader is referenced herein only as an
example of a typical muzzle-loading gun.
[0004] Improvements in high pressure gas control and the use of
high strength stainless steel in gun breeches has allowed the use
of modern smokeless powder propellants that generate higher gas
pressure in most guns, rather than low gas pressure black powder
propellants, or their substitutes, with the exception being
muzzle-loaders. Smokeless powder propellants have proven to be
preferable to black powder propellants for many reasons. The
ability to use smokeless powder propellants provides increased
versatility by making a greater variety of propellants available
for use in guns to meet the specific needs of any specific
occasions. The hazards of escaping black powder or black powder
substitute gases to the eyes of the gun user are eliminated,
because the strength of breeches required to contain the higher gas
pressures of smokeless powder propellants mandates that an
effective seal against high pressure gas escape be present. The
ease with which reloading can be accomplished is greatly increased,
because the fowling or residue left in gun barrels by black powder,
or its substitutes, is eliminated. Reliability is also increased to
the extent that misfires become a thing of the past; they almost
never happen with smokeless powders; whereas misfires plague many,
if not most, black powder propellants, or their substitutes. The
corrosion that is a partner of black powder propellants, or their
substitutes, is eliminated. If a gun can handle modern smokeless
powder propellants, greater accuracy and velocity are easily
achieved, which makes the gun much more desirable and valuable. The
hazards associated with the volatility, explosiveness, storage, and
transport of black powder, or its substitutes, are also eliminated,
and the legalities of black powder sales therefore need not be
considered.
SUMMARY OF THE INVENTION
[0005] The breech plug with primer pocket of the present invention
converts a black powder propellant muzzle-loading gun to a
smokeless powder propellant muzzle-loading gun by providing a close
fitting primer pocket wall, a flush fitting extractor that also
supports the primer's sides, and a primer pocket seat that is cut
at an angle of 25 degrees from the perpendicular of the primer
pocket wall to conform to the front face of the primer, such that
when the primer is seated against the primer pocket seat, a gas
seal is formed. A gas seal is also formed at the primer's side
walls, but to a lesser extent, because the primer swells or expands
under gas pressure, and since the primer's front seals the
propellant gases from further escape, the side walls of the primer
are of lesser importance. Thus, the one thousandth or two
thousandth clearance of the primer's side walls specified in the
preferred embodiment of the present invention that follows allows
easy ejection of the spent primer. More than the specified
tolerance will cause WINCHESTER brand primers, for example, to leak
around the primer walls.
[0006] A preferred embodiment of the present invention is a breech
plug with primer pocket for converting a black powder propellant
gun to smokeless powder propellants, comprising a smokeless powder
propellant breech plug sized to be closely removably fit within the
breech of a black powder propellant muzzle-loading gun, with a
breech opening at a first end of the plug and a primer pocket at a
second end of the plug, with apparatus to pass smokeless powder
propellant gas from the primer pocket to the breech opening,
wherein the primer pocket is substantially cylindrical in shape
with a diameter of about 0.2435 to about 0.2450 inches that is open
at the first end of the plug and that has a primer pocket seat at
the opposite end in direct communication with the apparatus to pass
smokeless powder propellant from the primer pocket to the breech
opening, the primer pocket seat having apparatus that conform the
shape of the primer pocket seat to the front face of a primer
filled with smokeless powder propellant to form a gas seal between
the primer pocket seat and the primer, and primer extractor
apparatus flushly fitted against the primer pocket to support a
primer wall and to eject a spent primer from the primer pocket.
[0007] Related objects and advantages of the present invention will
be clear from the following descriptions.
BRIEF DESCRIPTION OF THE DRAWING FIGURES
[0008] FIG. 1 is a segmented side view of the breech plug with
primer pocket and primer extractor of the present invention.
[0009] FIG. 2 is a left side view of the breech plug with primer
pocket and primer extractor of FIG. 1.
[0010] FIG. 3A is a rear view of the primer extractor of the
present invention.
[0011] FIG. 3B is a top view of the primer extractor of the present
invention.
[0012] FIG. 4 is a side view of the primer extractor of the present
invention.
[0013] FIG. 5 is a segmented bottom view of the left end of the
breech plug with primer pocket of FIG. 1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0014] Referring now to the drawing Figures, the machining
procedures for producing the preferred breech plug with primer
pocket 10 of the present invention for a THOMPSON-CENTER brand
209.times.0.50 muzzle-loading gun will be described for
illustrative purposes, only.
[0015] The procedure starts with a non-heated 17-4 PH stainless
steel rod 0.75 inches in diameter that will become the breech plug
with primer pocket 10 of the present invention. Start with a
convenient length of 17-4 PH. Place it in an indexing head on a
milling machine and cut 0.25 inches of {fraction (7/16)} inch hex
on one end. Place the rod into a true running chuck, and index to
less than 0.001 inches runout at about three inches from the chuck.
Face the end square. Center drill the end for a tailstock support
and apply a tailstock support.
[0016] All dimension numbers that follow are in inches, unless
stated otherwise. The primer pocket 18 dimensions given below are
the most critcal aspects of the breech plug with primer pocket 10
of the present invention.
[0017] Using the lengths provided in FIG. 1, cut the rod to the
specified diameters of 0.620, 0.681, and 0.691 inches. Thread the
middle section (0.681 inch diameter) at 20 threads per inch, with a
thread tool that is similar to the WITWORTH type thread form. Cut
the threads to nearly full depth. With a 0.157 inch diameter drill,
drill to a depth of 0.700 inch into the center of first end 14 of
the rod. Then with a drill of {fraction (27/64)} inches, drill
about 1/4 inch into the center of first end 14 of the rod. With a
ball nose end mill that has been ground to a diameter of 0.450
inches, round the resulting breech hole 16 in first end 14 to a
depth of about 0.300 inches.
[0018] At the first end 14 of the newly appearing breech plug with
primer pocket 10, use a parting tool and turn the diameter of the
breech hole 16 to 0.450 inches, being sure the cuts are square, and
that the length exceeds the overall length of the breech plug with
primer pocket 10 illustrated in FIG. 1 (1.320 inches). The length
at the {fraction (11/16)} inch shoulder should be about 1.115
inches. Be sure to leave excess length needed for the width of the
parting tool to cut it off. Remove the rod from the lathe chuck and
use a wire brush to clean up the thread. The rod should then screw
into the threaded end of the THOMPSON-CENTER gun barrel. Anti-seize
or lots of oil should be used, and if there is any bind, dimensions
must be a slip fit. If the rod seats against the gun barrel
shoulder, torque to 30 ft. lbs.
[0019] Place the rod into the indexing head of the gun with a less
than tight fit, and with the head set on zero, level the lug of the
gun barrel. Tighten the jaws on the indexing head. Remove the
barrel by unscrewing it. Set the indexing head to -7 or -8 degrees,
and cut the flats of a {fraction (7/16)} inch hexagon into the
second end 12 of the rod.
[0020] Remove the rod from the indexing head and cut it off a
measured length longer than the specified overall length for the
breech plug with primer pocket 10 illustrated in FIG. 1 (1.320
inches). Place the threaded end into a four jawed chuck on the
lathe and index it to less than 0.001 inch runout. Aluminum or
brass shim is optional, 17-4 PH is tough even when non-hardened,
and a little gentleness on the t-bar of the chuck will keep any
damage from occurring.
[0021] Face the rod's second end 14 off the measured amount (FIG.
1) so that an overall length of 1.320 inches is obtained. Some
muzzle-loading guns may require the length to be as short as 1.318
inches. Testing in each gun might be necessary. The rod must close
in the gun when torqued with a 0.0015 inch feeler between the rod
and the gun's breech face.
[0022] With the rod indexed at 0.001 inch or less runout, drill
into the second end 12 face with a small center drill. Then drill
to a depth of 0.320 inch with a #2 drill. With a boring tool that
has a 25 degree lead angle, bore to a depth of 0.299 to 0.306 inch.
The resulting diameter of primer pocket 18 must be 0.2435 inch to
0.2450 inch. The creation of primer pocket 18 is best achieved if
done in more than one step.
[0023] The resulting 130 degree included angle is at the seat or
bottom 26 of the primer pocket 18. This is the actual angle
produced by cutting the sides and bottom of the primer pocket with
a cutting tool having a 25 degree lead angle. The resulting shape
of the primer pocket 18 seat or bottom 26 now conforms to the front
of a smokeless powder primer, thus effecting a seal when a primer
is placed in the primer pocket 18. The angle does not need to be
exactly 25 degrees, but this seems to be the optimum angle from
testing that has been done to date.
[0024] Drill a flash hole through the center of the resulting
breech plug with primer pocket 10 with a #55 or a {fraction (3/64)}
inch drill bit. Cut the specified primer rim countersink 28 and
chamfer 30 into the second end 12, as illustrated in FIGS. 1 and 5.
A primer extractor cut 17 square with a flat of the {fraction
(7/16)} hexagon at the second end 12 must be cut into a flat of the
hexagon at second end 12 of the breech plug 10 (FIG. 5). This will
allow the primer extractor, discussed below, to be fit flush with
the corresponding wall of the primer pocket 18, thereby supporting
the primer's side wall as well, as illustrated in FIG. 1.
[0025] Heat treat the breech plug 10.
[0026] Screw the breech plug with primer pocket 10 into the gun's
barrel, again well-lubed, and torque to 50 ft. lbs. The hardened
metal is less likely to gall, and is dimensionally slightly smaller
than the untreated metal. The extractor cut 17 should be square at
the bottom of breech plug with primer pocket 10.
[0027] Measure the distance from the bottom of the extractor cut 17
to the bottom of the primer pocket 18. This distance is the height
of the primer extractor 20 at the bottom of the 0.2435 inch
diameter of the primer pocket 18. The overall height of the primer
extractor 20 should be about 0.545 inch. If it is different on any
gun, it must be made to match the specific gun in question.
[0028] Place the THOMPSON-CENTER gun barrel with the breech plug
with primer pocket 10 in place in a suitable fixture and center a
six millimeter carbide end mill to make the extractor cut 17 under
the hexagon on the second end 12 of breech plug with primer pocket
10, in the lug area of the barrel. With lube, mill the breech plug
with primer pocket 10 in place to a depth of 0.090 inch. Remove the
barrel from the fixture and de-burr the newly made extractor cut
17.
[0029] The primer extractor 20 is mated to the diameter of the
primer pocket 18, and supports a primer wall from expansion under
high pressure. The primer extractor 20 can be of semi-circular or
full circular design and still accomplish this end. If it is
semi-circular, it must be fitted to bear against a solid surface in
order to be stationary enough to support a primer, and its sides
must be mated to a recess within the primer pocket, as illustrated
in the drawing figures. While the idea of a circular extractor may
have been utilized in the past with the extractors of some obscure
rimfire cartridge chambers, its use for primers is entirely new.
Also the diameter must match the primer pocket 18 exactly or be no
greater than the maximum primer pocket 18 diameter listed above
(not the less critical and considerably smaller diameter of the
previously mentioned rimfire cartridge case).
[0030] Hacksaw or otherwise saw a piece of 3/4 inch.times.1/4 inch
oil hardening tool steel to approximate the primer extractor 20
dimensions that are shown in FIG. 4.
[0031] Finish the dimensioning with an end mill so that all
surfaces are square and so that the upper part of the primer
extractor 20 is narrowed to about 0.230 inch.
[0032] Turn the primer extractor 20 so that the long part is
verticle, and so the end or lip that will contact primers is clear
of the vise. With an end mill or other cutter that is 0.244 inch in
diameter, cut in such a manner that the center of the cut is along
the center of the primer extractor 20 until the above-measured
0.545 distance is achieved in the most central part of the cut. Put
a {fraction (5/16)} inch end mill in the machine and cut a
countersink to match countersink 28 by moving the cutter about
0.015 inches forward and plunging 0.020 inches (or up to 0.027
inches).
[0033] The primer extractor 20 arm must be reduced in thickness
from 0.130 to 0.090 on the front facing, breech-plug-touching
surface so that it clears the breach plug with primer pocket 10 at
the 0.130 inch thickness.
[0034] The bevel 22 must be milled; the exact angle is not
critical. The length of the cut is specified in FIGS. 3 and 4.
[0035] A cut 24 for a primer extractor 20 limit screw must be
made.
[0036] The primer extractor 20 must fit into the gun's breach while
still installed in the gun barrel.
[0037] The area of primer extractor 20 that should touch a primer
should be either very close or exactly flush with the primer pocket
18 walls. If not, light lapping should clean it up. For this
reason, holding to the tightest tolerance on the primer pocket 18
diameter is best.
[0038] Heat treat the primer extractor 20, and clean and assemble
the new parts and the gun.
[0039] The firing pin protrusion must not exceed 0.060 inch; 0.055
inch is sufficient.
[0040] If the boring tool with the 25 degree lead angle was used to
create primer pocket 18 to a depth of 0.299 inch, which is a very
shallow primer pocket 18, considerable force is necessary to close
the gun's action when a primer happens to be on the long side of
the tolerance scale (0.304 inch), with only moderate force required
to close the action on a short primer (0.299 inch). On the other
hand, if the primer pocket 18 is cut to a depth of 0.306 inch,
short primers seal anyway, and no force is required to close the
gun's action. Primers still seal on the seat or bottom 26 of the
primer pocket 18. Evidently the force of the firing pin seals the
primer pocket 18 by forcing a primer forward at the time of
ignition. Even the longest primers in a sample of WINCHESTER brand
W209 closed with no force in addition to the force normally needed
to close the gun's action. All of them sealed with a 0.306 inch
depth primer pocket 18. Also, when the primer pocket 18 is deepened
to the maximum tolerance (which would appear to be the most
practical), the primer rim counter sink 28 must be made
correspondingly deeper also. A depth of 0.026 inch or 0.027 inch is
then correct.
[0041] The information about primers is provided because there
seems to be a lot of variation in the length of primers from just
one company, not to mention all the brands not tested to date.
There is much more variation among older primers of the same
manufacturer than in newer ones. The point is that primers of
different lengths all seem to seal in a slightly long 0.2435 inch
to 0.245 inch diameter primer pocket 18 if the seat 26 has the 130
degree included angle (cut with a boring bar with a 25 degree lead
angle) that conforms to the primer's frontal shape.
[0042] The procedure for loading the THOMPSON-CENTER brand 209-0.50
muzzle loader is the same as it would be for any break-open type
firearm into which the conversion of the present invention has been
fitted. The procedure would also apply to any falling block firearm
into which the conversion of the present invention has been fitted.
The conversion system of the present invention will work
wonderfully well in falling block actions so long as the primer
extractor 20 can be supported opposite a primer so that the primer
is contained under pressure, and not allowed to expand beyond the
dimensions of the primer pocket 18.
[0043] Bolt actions can also be fitted with the conversion system
of the present invention. A circular prime extractor that
encompasses and supports a primer through 360 degrees, fitting
between a shortened breech and the bolt face may be beneficial
because it allows the bolt to rotate in and out of battery, while
keeping a primer fully supported. To load, one must always open or
expose the action, thus exposing the breech. It is helpful to place
a dummy primer into the breech and close the action. When
reloading, the previous shot's spent primer will also suffice. This
prevents smaller granules of certain types of propellant powders
from falling through the flash hole and into the works of the
gun.
[0044] In many instances the powder charge would need to be
pre-measured or pre-weighed, with sabots being recommended.
[0045] The conversion system of the present invention can still be
used with black powder, if one would so choose.
* * * * *