Solving the Problems of the Prior Art Need to Oversize Weapon Bores and Loss of Accuracy Thereof

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Application No. 63/723,355, filed Nov. 21, 2024, the content of which is incorporated herein by reference in its entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable.

FIELD OF THE INVENTION

The present invention relates to solving the problem of the prior art need to oversize weapon bores such as, but not limited to, rifle barrel and sleeve bores, and pistol and machine gun bores; and thin-dense chrome coated nitrided bores thereof.

BACKGROUND OF THE INVENTION

The effectiveness and accuracy of kinetic weapons depend to a large extent in maintaining the dimensions of their respective bores at very close to original dimensions, this applies to, for example, rifled rifle bores, rifled sleeve bores (and hereafter rifled pistol and machine gun bores, and rifled weapons up to the howitzer class).

Weapon bores typically have either a nitrided or a chrome-lined surface, but generally not both on the same barrel. These are two distinct and competing barrel treatment processes, each with its own advantages. The problem with the chrome layer of the prior art is that the thickness of the chrome layer is such that, for example, rifle barrels and sleeves of the prior art have to be oversized to accommodate the thickness of the chrome layer. Another issue is that the prior art chrome layer suffers from, for example, spalling, and wear in barrels (and sleeves) leading to a drop off in accuracy in turn requiring replacement of, for example, rifle barrels. There is a need to address both these issues.

SUMMARY

The present invention relates to rifled weapon bores, such as those of kinetic weapons that, at least in part, use kinetic energy to penetrate or destroy a target. Examples range from traditional firearms firing bullets up to and including mortars and large caliber kinetic weapons such as howitzers. So, the present invention speaks to rifled bores of barrels and sleeves (hereinafter this also applies to the rifled bores of pistols and machine guns (and as stated, larger caliber weapons up to howitzer class weapons) having a nitrided interior surface with a layer of thin dense chrome deposit thereon.

The inventor has discovered that a thin dense layer of chrome having thickness of 0.0001 to 0.0002 inches, and preferably 0.0001 inches, unexpectedly falls within the tolerance of the rifled bore of the barrel (and sleeved bore) as specified by the manufacturer, and the thin dense chromed rifle barrels, and sleeves, of the present invention unexpectedly do not need to be oversized as is the case with respect to chromed bores of the prior art (with a standard thickness 0.001 to 0.005 inches). The additional benefit of the hardness of the rifle barrels and sleeves of the present invention unexpectedly lead to a reduction in loss of accuracy and so do not have to be replaced as often as chromed barrels (and sleeves) of the prior art.

In essence, the present invention is focused on the unexpected benefits of thin dense chrome deposited on nitrided internal rifled bore surfaces which unexpectedly overcomes the problem of needing to over-size the diameter of rifle bores (smooth or rifled), sleeve bores (and pistol and machine gun bores) up to larger caliber weapons up to howitzers.

It should be understood that the weapon bores of the present invention are rifled weapon bores as opposed to smoothbore weapons. (A rifled bore is the interior of a weapon barrel that has been machined with helical (spiral) grooves along at least part of its length. The primary purpose of these grooves is to impart a stabilizing spin to the projectile as it travels down the barrel and exits the muzzle.) Henceforth, all mentions of the terms “bore” or “bores” explicitly refer to rifled weapon bores.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A shows a schematic cross-section view of a rifle barrel according to the present invention.

FIG. 1B shows an enlarged schematic view of the rifle barrel of FIG. 1A according to the present invention.

FIG. 2 shows a schematic cross-section view of a sleeve according to the present invention.

FIG. 3 shows a schematic cross-section view of a machine gun barrel according to the present invention.

FIG. 4 shows a schematic cross-section view of a large caliber barrel having a bore diameter in the range 20 mm to 60 mm according to the present invention.

FIG. 5 shows a schematic cross-section view of a sub-howitzer weapon barrel having a bore diameter in the range 61 mm to 100 mm according to the present invention.

FIG. 6 shows a schematic cross-section view of a howitzer barrel having a bore diameter in the range 105 mm to 155 mm according to the present invention.

FIG. 7 shows a schematic cross-section view of an aluminum piston cylinder according to the present invention.

FIG. 8 shows a schematic cross-section view of a steel engine cylinder according to the present invention.

FIG. 9 shows a schematic cross-section view of aerospace aluminum tubing according to the present invention.

FIG. 10 shows a schematic cross-section view of aerospace steel tubing according to the present invention.

FIG. 11 shows a schematic cross-section view of a pistol barrel according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The problem of the prior art is that the thickness of the chrome layer is such that, for example, rifle barrels and sleeves have to be oversized to accommodate the thickness of the prior art chrome layer whilst also maintaining accuracy of the weapon. The inventor has unexpectedly achieved success on both fronts.

For the purposes of the present invention a rifle is defined as a long-barreled firearm designed to be fired from the shoulder; and a sleeve is a barrel liner, typically a pre-rifled tube that is inserted into the bore of an existing, often worn-out or damaged, barrel of a weapon such as, but not limited to, a rifle.

It should be understood that the weapon bores of the present invention are rifled weapon bores as opposed to smoothbore weapons. (A rifled weapon bore, as defined herein, is the interior of a weapon barrel that has been machined with helical (spiral) grooves along at least part of its length. The primary purpose of these grooves is to impart a stabilizing spin to the projectile as it travels down the barrel and exits the muzzle. ) Henceforth, all mentions of the terms “bore” or “bores” explicitly refer to rifled weapon bores.

The prior art chrome layer is uneven due to the fact it is a thick deposit which varies between 0.001 to 0.005 inches, which is outside the tolerance of the bore of the barrel (and sleeved bore) specified by the manufacturer and hence the manufacturer has to oversize the bores of the prior art; i.e., increase the diameter of the bores of the prior art. The inventor has unexpectedly discovered and solved this problem by coating nitrided internal surface of weapon bores such as those of rifles (and sleeves) with a thin dense chrome deposit with a thickness in order of 0.0001 to 0.0002 inches. More specifically, the inventor unexpectedly discovered that a thin denser layer of chrome having thickness of 0.0001 to 0.0002 inches is unexpectedly within the tolerance of the bore of the barrel (and sleeved bore) as specified by the manufacturer, and the chromed rifle barrels, and sleeves, of the present invention unexpectedly do not need to be oversized. Thin dense chrome is a metallic chromium coating applied to a metal base through electroplating. The primary material of thin dense chrome is pure chromium.

That prior art bores having a chrome layer of standard thickness 0.001 to 0.005 inches have to be oversized to accommodate the thickness of the prior art chrome layer which in turn interferes with the manufacturing process, whereas the application of a thin dense chrome deposit (i.e., layer thereof) of the present invention on a nitrided inner bore surface unexpectedly cures this problem such that the manufacture of chromed rifle barrels (and sleeves) of the present invention is more streamlined compared to the manufacture of chromed rifle barrels (and sleeves) of the prior art which have to be oversized.

In addition, in the thicker plating process of the prior art result in relatively large cracks, voids and porosity issues, a common issue on surfaces deposited with the prior art chrome layer. In contrast, the inventor unexpectedly found that thin dense chromed rifle barrel bores (and sleeves) of the present invention are not micro-cracked deposits and do not have the porosity and uneven nature of prior art chromed rifle barrel bores (and sleeves).

Moreover, that prior art chrome layer is thick and characterized by the presence of, for example, voids; this means the prior art chrome is uneven in contrast to the thin dense chrome (deposit on a nitrided surface) of the present invention which forms an even surface and offers no detriment to accuracy of fired rounds.

The inventor discovered unexpectedly that chromed bores of the prior art are less heat resistant compared to the bores of the present invention wherein thin dense chrome applied to nitrided bore surfaces provides the unexpected property of high heat resistance without detracting from the accuracy of the rifle bore (and sleeve bore).

Thin dense chrome plating over nitrided barrel and sleeve bores of the present invention also unexpectedly improves wear resistance, which unexpectedly translates to reduction in loss of accuracy, because thin dense chrome plating of the present invention results in fewer surface cracks, fewer inclusions, and fewer voids, collectively reducing the rate of heat and corrosive attack, and provides more resistance to fragmentation, spalling, and wear in barrels (and sleeves).

The hardness of the interior surface of firearm barrels (and sleeves) of the present invention is unexpectedly in the range of 71 RC to 73 RC, and preferably 73 RC (where the “R” in “RC” is abbreviation of “Rockwell”) compared with prior art chromed barrels and sleeves having a hardness of 70 RC.

With a hardness in the range of 71 RC to 73 RC combined with the benefits of the thin dense chrome (for example, fewer surface cracks, fewer inclusions, and fewer voids compared to prior art) additionally means chromed rifle bores (and sleeved bores) of the present invention unexpectedly allow more rounds to be fired before a barrel (and sleeve) is worn and needs to be replaced compared to chromed barrels (and sleeves) of the prior art.

Nitriding of internal surfaces of bores can be achieved by heating and applying a gaseous mixture of ammonia, nitrogen, and hydrogen which is brought into contact with the internal surfaces of bores to produce a nitrided surface thereon. That is, the process of nitriding the internal surface of bore metal can be performed by heating the bore metal in a nitrogen-rich environment to allow nitrogen atoms to diffuse into the surface of the bore metal; specifically, nitrogen reacts with steel and diffuses into the steel creating nitrides. In the schematic shown in FIG. 1D (which is not to scale) the nitrogen atoms diffused into an internal surface 140 are represented by dots. Nitriding does not alter the dimensions of the bore whereas applying a prior art layer of chrome to the nitrided surface does alter the dimensions of the bore. Thin dense chrome can be applied to nitrided surfaces by electroplating or physical vapor deposition (PVD) thereon.

The present invention is, inter alia, directed to a rifle barrel 100 (see FIG. 1A, which shows a sectional view thereof according to the present invention). Specifically, the rifle barrel 100 defines a rifle bore 120, the rifle bore 120 comprises a nitrided internal surface 140 and a layer of thin dense chrome 160 deposited thereon (see schematic shown in FIG. 1B; “dots' in FIG. 1B represent nitrogen atoms which form part of the nitrided internal surface 140 of the barrel 100). The layer of thin dense chrome 160 having a thickness of 0.0001 to 0.0002 inches. The layer of thin dense chrome 160 (deposited on the nitrided internal surface 140) preferably has a thickness of 0.0001 inches.

The present invention is also directed to a sleeve 200 (which is a barrel liner, typically a pre-rifled tube that is inserted into the bore of an existing, often worn-out or damaged, barrel of a weapon such as, but not limited to, a rifle). Specifically, the sleeve 200 defines a sleeve bore 220, the sleeve bore 220 having a nitrided internal surface 240 and a layer of thin dense chrome 260 deposited thereon (see schematic shown in FIG. 2), the layer of thin dense chrome 260 having a thickness of 0.0001 to 0.0002 inches. The layer of thin dense chrome 260 (deposited on the nitrided internal surface 240 of the sleeve 200) preferably has a thickness of 0.0001 inches.

The present invention is also directed to a weapon in the form of a machine gun. Specifically, a machine gun defines a machine gun barrel 300, the machine gun barrel 300 defines a machine gun bore 320 (the machine gun bore 320 having a diameter in the range 4.6 mm (0.18 inches) to 14.5 mm (0.57 inches), where “mm” stands for millimeters. The machine gun bore 320 comprises a nitrided internal surface 340 and a layer of thin dense chrome 360 deposited thereon (see schematic shown in FIG. 3). The layer of thin dense chrome 360 having a thickness of 0.0001 to 0.0002 inches. The layer of thin dense chrome 360 (deposited on the nitrided internal surface 340) preferably has a thickness of 0.0001 inches.

The present invention is also directed to a larger caliber weapon comprising a large caliber barrel 400, the larger caliber barrel 400 defining a large caliber weapon bore 420 in the diameter range 20 mm to 60 mm (where “mm” stands for millimeters). Weapons in the diameter range 20 mm to 60 mm are typically classified as autocannons, cannons, or mortars, rather than small arms, and are widely used on military vehicles, aircraft, and ships. Specifically, the present invention is directed to a large caliber weapon bore 420 (20 mm to 60 mm) comprising a nitrided internal surface 440 and a layer of thin dense chrome 460 deposited thereon (see schematic shown in FIG. 4), the layer of thin dense chrome 460 having a thickness of 0.0001 to 0.0002 inches. The layer of thin dense chrome 460 preferably has a thickness of 0.0001 inches.

The present invention is also directed to a sub-howitzer weapon having a sub-howitzer weapon barrel defining a sub-howitzer weapon bore 520 in the diameter range 61 mm to 100 mm (where “mm” stands for millimeters); these are typically found primarily in the category of mortars and artillery. Specifically, a sub-howitzer weapon defines a barrel 500 with a weapon bore 520, the sub-howitzer weapon bore 520 comprising a nitrided internal surface 540 and a layer of thin dense chrome 560 deposited thereon (see schematic shown in FIG. 5). The layer of thin dense chrome 560 having a thickness of 0.0001 to 0.0002 inches. The layer of thin dense chrome 560 (deposited on the nitrided internal surface 540) preferably has a thickness of 0.0001 inches.

The present invention is also directed to a howitzer weapon. Howitzers come in different mobility types, including towed, self-propelled (SPH), and truck-mounted. The caliber range for howitzers is wide, but modern, common calibers typically have bore diameters between 105 mm and 155 mm (where “mm” stands for millimeters). Specifically, a howitzer defines a howitzer barrel 600 itself defining a howitzer bore 620, the howitzer bore 620 comprising a nitrided internal surface 640 and a layer of thin dense chrome 660 deposited thereon (see schematic shown in FIG. 6). The layer of thin dense chrome 660 having a thickness of 0.0001 to 0.0002 inches. The layer of thin dense chrome 660 (deposited on the nitrided internal surface 640) preferably has a thickness of 0.0001 inches.

The present invention is also directed to an aluminum engine piston. Specifically, an aluminum engine piston defines an aluminum piston cylinder 700 which itself defines an aluminum piston bore 720, the aluminum piston bore 720 comprises a nitrided internal surface 740 and a layer of thin dense chrome 760 deposited thereon (see schematic shown in FIG. 7). The layer of thin dense chrome 760 having a thickness of 0.0001 to 0.0002 inches. The layer of thin dense chrome 760 (deposited on the nitrided internal surface 740) preferably has a thickness of 0.0001 inches.

The present invention is also directed to a steel engine piston. Specifically, the steel engine piston defines a steel engine cylinder 800 which itself defines a steel piston bore 820, the steel piston bore 820 comprises a nitrided internal surface 840 and a layer of thin dense chrome 860 deposited thereon (see schematic shown in FIG. 8). The layer of thin dense chrome 860 having a thickness of 0.0001 to 0.0002 inches. The layer of thin dense chrome 860 (deposited on the nitrided internal surface 840) preferably has a thickness of 0.0001 inches.

The present invention is also directed to aerospace aluminum tubing 900 (for example, high-strength aluminum alloys from the 2000, 6000, and 7000 series (e.g., 2024, 6061, 7075), which meet standard ASTM B210, wherein “ASTM” stands for “American Society for Testing and Materials”). Specifically, the aerospace aluminum tubing 900 defines an aerospace aluminum tubing bore 920, the aerospace aluminum tubing bore 920 comprising a nitrided internal surface 940 and a layer of thin dense chrome 960 deposited thereon (see schematic shown in FIG. 9). The layer of thin dense chrome 960 having a thickness of 0.0001 to 0.0002 inches. The layer of thin dense chrome 960 (deposited on the nitrided internal surface 940) preferably has a thickness of 0.0001 inches.

The present invention is also directed to aerospace steel tubing 1000 (for example, that meets AMS (Aerospace Material Specification) ). Specifically, the aerospace steel tubing 1000 defines an aerospace steel tubing bore 1020, the aerospace steel tubing bore 1020 comprises a nitrided internal surface 1040 and a layer of thin dense chrome 1060 deposited thereon (see schematic shown in FIG. 10). The layer of thin dense chrome 1060 having a thickness of 0.0001 to 0.0002 inches. The layer of thin dense chrome 1060 (deposited on the nitrided internal surface 1040) preferably has a thickness of 0.0001 inches.

The present invention is also directed to a weapon in the form of a pistol (a pistol being a small firearm designed to be held in one hand). Specifically, the pistol defines a pistol barrel 1100 which itself defines a pistol bore 1120, the pistol bore 1120 comprises a nitrided internal surface 1140 and a layer of thin dense chrome 1160 deposited thereon (see FIG. 11). The layer of thin dense chrome 1160 having a thickness of 0.0001 to 0.0002 inches. The layer of thin dense chrome 1160 (deposited on the nitrided internal surface 1140) preferably has a thickness of 0.0001 inches.

TEST FIRING

One shooter, four barrels. All barrels identical except for internal surface finish.

• • Barrel 1. Bare cold hammer forged 4150 chromium, molybdenum, vanadium steel.
  • Barrel 2. Nitrided cold hammer forged 4150 chromium, molybdenum, vanadium steel.
  • Barrel 3. Thin Dense Chrome (0.0001 inch thickness) Plated cold hammer forged 4150 chromium, molybdenum, vanadium steel.
  • Barrel 4. Thin Dense Chrome (0.0001 inch thickness) over nitrided cold hammer forged 4150 chromium, molybdenum, vanadium steel.

Protocol

Each barrel provided a ten round initial sample group. Barrels were shot in strings of 250 rounds with adequate cooling every 50 rounds and 15 minutes between each 250 round string. At 1,000 rounds the bores were cleaned and a ten round group was recorded. When the group size was double the size of the original test group size, the barrel was excluded. (Test firings completed over a 10 day period.) Each barrel was that of a machine gun with the dimensions: 5.56 mm×45 mm NATO (i.e. bullet diameter 5.56 mm×case length 45 mm) based on the original .223″ Remington commercial cartridge. The initial group sizes of all four barrels were statistically identical.

Results

• • Barrel 1:6,100 rounds fired whereupon the group size was double the size of the original test group size, and so this barrel was excluded.
  • Barrel 2:15,700 rounds fired whereupon the group size was double the size of the original test group size, and so this barrel was excluded.
  • Barrel 3:31,400 rounds fired whereupon the group size was double the size of the original test group size, and so this barrel was excluded.

Barrel 4:58,500 Rounds Fired*

*The testing was terminated at this point because the barrel was still grouping with the accuracy limits set.

Conclusion

Barrel 4 with 0.0001 inch thin dense chrome over a nitrided surface totally outperformed each other listed barrel including barrel 3 with thin dense chrome plated cold hammer forged 4150 chromium, molybdenum, vanadium steel demonstrating the unexpected finding that thin dense chrome over a nitrided surface offers greatest accuracy even after firing significantly more than 31,400 rounds. More specifically, even after firing 58,500 rounds barrel 4 was still performing to spec and showed no signs of needing to be replaced thus demonstrating the unexpected performance of a nitrided surface with thin dense chrome deposit thereon; the thin dense chrome having an optimum thickness of 0.0001 inches.

The invention has been described herein with reference to particular exemplary embodiments. These exemplary embodiments are meant to be illustrative, and the invention is not limited to the examples provided. Certain alterations and modifications will be apparent to those skilled in the art, without departing from the scope of the invention. Accordingly, the scope of the invention is limited only by the appended claims.