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20mm Vulcan Rifle
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Write me at FIFTYGUY@aol.com
The PTRD(ProtivoTankovoe Ruzhiyo Degtyarev) is a WWII Russian antitank gun. Designed by Degtyarev, it is a single-shot self-ejecting bolt action rifle chambered for the 14.5x114mm Russian cartridge. I replaced the original barrel with one from a 20mm M61 Vulcan cannon, and added a 35 lb weight to reduce the recoil of the more powerful 20mm rounds. Here are a few photos from the test-firing session (click on thumbs for full-size version):
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Me at the range. Muzzle of the Vulcan barrel, with the weight screwed over it. Weight is internally threaded at both ends, and provides a mounting point for muzzle devices (recoil brake, future silencer). |
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Here is my PTRD as I first saw it, on Kent Lomont's table at the April 1998 Knob Creek Machinegun Shoot. I didn't even recognize it until I got home and developed the film. |
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The PTRD in original configuration, with the 14.5mm barrel. |
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The barrel and action are spring-loaded against the tubular buttstock. During recoil, the bolt handle hits the unlocking cam on the right side of the gun. This unlocks the bolt and allows it to fly open to the rear. The spent casing ejects out the bottom of the gun. A new round can be slid into the chamber through the hole in the top, and the bolt then manually closed for another shot. |
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The original 14.5mm barrel is on the left, the modified 20mm vulcan barrel with weight is on the right. |
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LEFT: The PTRD bolt (12" long). The firing pin has a hook to allow re-cocking in the event of a misfire. The smaller round is a 14.5mm API. The larger is an ARES low-drag TP-T. RIGHT: the ARES TP-T at top, with the 5 test rounds. The M103 casings have their rims ground down to fit the unmodified bolt. Powder is 560-570-580-590-600 grains of WC872. Primers are M36A2, projos are M55 TP. |
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With the Vulcan barrel installed. Note the35 lb weight screwed on the barrel. The butt is propped against a 2x4 in a 5 gallon bucket of concrete. After the 5 test shots, the bucket had moved back 2 inches in the ground! You can see the door lock solenoid and wire used for remote-firing. |
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Here I am sighting the gun before it is remote-fired. At that time, the Vulcan barrel had no sights of any kind, and the design prohibited boresighting without a mirror. Luckily, the target was only 15 yards away. |
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I only had one round of 14.5mm to shoot (an Armor-Piercing Incendiary, unidentified origin). I wanted to shoot a reactive target, and this glass piggybank fit the bill. The coins scattered over a 30 foot radius, and the 14.5's AP core snapped from the stress (only the front half was recovered). |
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20mm TP round hits the target. We shot a variety of targets, including a bag of jelly donuts with a .50 BMG incendiary round, a boom box, several bowling pins, and a box of jelly donuts. The dirt from the berm landed as far as 50 yards away. |
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Another direct hit. Note the white smoke from the gun, and the plume of dirt from the berm. The white objects on the berm are bowling pins. The M55 TP projos exploded like conventional soft point bullets. They are constructed like soft points, except they are made of steel and aluminum, instead of copper and lead. |
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Recovered projectile pieces. LEFT TO RIGHT: .50 BMG AP round, .50 BMG case and recovered AP core. 14.5mm case and recovered front half of API core. Torn and mangled pennies and a quarter from piggybank are above it. Two 20mm test round casings, and pieces of the M55 TP projos. Unfired 20mm test round. Some recovered intact loose change. .50 BMG rifle is at far right, 14.5mm barrel at bottom. |
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PTRD with 20mm vulcan barrel and original bipod. 14.5mm barrel is below. Note the dollar bill below for size comparison. |
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LEFT: The PTRD bolt, with the firing pin assembly removed. CENTER: .30-06 subcaliber insert that had been welded into the 14.5mm barrel when I had bought the gun. 14.5mm unfired API round. Unloaded case and projo from 20mm test ammo. Electrically primed 20mm Vulcan round, ARES low-drag percussion primed TP-T round. RIGHT: Box of 112 M36A2 20mm/30mm percussion primers, dollar bill for size comparison. |
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Weight removed from the Vulcan barrel. Note how thin-walled the Vulcan barrel is, designed to save weight. 5 years ago they re-designed them to be even skinnier! |
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My State Arms .50 BMG rifle. Pretty, ain't she? I traded her for a L.A.R. Grizzly Big Boar .50. |
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Since these pics were taken, I've:
- Welded a reinforcing plate to the sheetmetal butt.
- Drilled a hole in the butt for boresighting with the bolt removed.
- Replaced the felt and canvas buttpad with a silicone foam pad.
- Lapped in the locking lugs. Originally at about 20 percent contact area.
- Made a mount for a long eye-relief scope to the Vulcan barrel.
- Gone to a red-dot handgun scope. Now if I can just keep the mount bolts from loosening...
- Added a muzzlebrake that came from an A4 SkyHawk's Mk12 20mm (Mk100) cannon.
- Opened the loading and ejection ports in the receiver to accomodate the 20mm rounds.
- Had the bolt face opened up to fit the 20mm's larger rim diameter.
- Made a new bipod.
- Made yet another bipod. Recoil destroys even sturdy bipods.
- Fired M95 Hispano AP-T projos.
- Fired Oerlikon inert projos (cheap!)
- Loaded tracer elements into standard TP projos. Work great, very bright.
I plan to build a silencer for the rifle.
Needless to say, it'll be one massive can!
I'll also eventually have a system that will
allow it to fire electrically primed ammo. I
need to precisely fit the inside of muzzlebrake
adaptor to prevent barrel whip, as that seems
to be killing any accuracy potential.
Other projects include:
- 40mm Bofors AA gun (longer-term project, beginning with a lightweight single-shot version)
- 57mm Recoilless Rifle (free splitting headache with every shot)
- 81mm Mutt Mortar (mongrel collection of various parts, but works nicely)
- Bowling Ball Mortar (thank you for the help, Bob!)
- High Voltage/High Energy projects - see what goes on at "This End of the Block"!
Write me at FIFTYGUY@aol.com |
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Visit these sites:
Serbu Firearms - the Class II Manufacturer who machined my Vulcan barrel and weight. Maker of the SIRIS integrally suppressed .22 pistol, the 6.5"-barrelled Super Shorty pump shotgun (I have one - great fun and handy), and the affordable BFG-50 bolt-action .50 BMG rifle (very fun, lightweight, and accurate). Now making the BFG-50A affordable semi-auto .50 BMG rifle. Don't be fooled by imitators - you won't find better quality at any price. Production 20mm Vulcan rifles a future possibility.
Kent Lomont - Dealer and Manufacturer of Destructive Devices and Machine Guns
River Valley Ordnance Works - sells both large and small caliber ammo and components.
Russian 14.5 mm antitank rifle PTRD-1941 - from a site on weapons of the Korean War.
Old Western Scrounger - sells ammo in rare and hard-to-find calibers.
Virginia Beach Rifle and Pistol Club - if you're a doddering octogenarian who believes the NRA's propaganda that the 2nd Amendment only protects duck hunters and cowboy action shooters, this is the club for you.
PanzerSchrek and PanzerFaust - site with info on antitank weapons, including the PTRD.
Fifty Caliber Shooters' Assc. - Association of shooters of the .50 BMG and other large cartridges.
Brashco Specialty Ammunition - sells Oerlikon and Hispano-Suiza brass, as well as new electrically primed Vulcan brass. Also sells Vulcan TP projos, and loaded electrically primed Vulcan TP ammo.
Anti-Tank Rifle Discussion Board at Obscure-Reference.com - a nice place for advice and networking if you've got a project or a big gun for sale.
L.A.R Manufacturing - makes the Grizzly Big Boar .50 BMG rifle.
Big Sky Surplus - sells surplus ammo, components, and cannon parts for the shooter and collector.
Springfield Arsenal - sells surplus ammo, components, and cannon parts for the shooter and collector. Also has tools and trench art.
Destructive Devices Forum at Impact Guns - Forum run by Destiny, mainly to chronicle her ongoing 57mm Recoilless Rifle project. Terrific collection of pics and info on the 57mm (and 75mm) RCLs.
NitroRacer.com - Site I did for a friend of mine. He races a Top Fuel motorcycle with a V-8 engine that makes over 1000 horsepower. Zero to 240 mph in 6.5 seconds!!(site currently inactive)
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