J.D. Jones' .50 Peacekeeper Rifle Cartridge in Review

Anti-materiel rifles chambered for the .50 Browning Machine Gun (12.7x99mm NATO) cartridge have long been of interest to both shooters and collectors. While many shooters love the brute power and performance of this big cartridge, it does come at a price. The downside to .50 BMG rifles like Barrett’s M82, besides their recoil and blast, is simply their size and weight. They are physically large and very heavy which makes them less mobile. One person who took note of this over 20 years ago was J.D. Jones of SKK Industries. He responded by developing the little known .50 Peacekeeper cartridge. This was designed to provide 80% of the power of a .50 Browning Machine Gun cartridge while fitting into a conventional size and weight rifle. How about a 650-grain bullet launched at 2,400 fps from a 13-pound rifle?

For this column I decided to roll back the pages of time and re-examine this interesting design capable of firing heavy Armor Piercing, Armor Piercing Incendiary and Armor Piercing Incendiary Tracer projectiles. J.D. based his .50 Peacekeeper cartridge on Roy Weatherby's impressive .460 Weatherby Magnum. Introduced in 1958, Roy's .460 was designed for one purpose, to take over the title of the World's most powerful commercial cartridge. He accomplished this by necking his .378 Weatherby case up to .458. Factory ammunition was advertised at pushing a 500-grain bullet at a bone crushing 2,700 fps generating 8,095 ft-lbs of muzzle energy. More than enough power to knock the British .600 Nitro Express (which churns up a mere 7,600 ft-lbs) from its throne. With a pull of the trigger Roy's .460 WM handed out judgment on big game animals in a manner not seen outside of Old Testament fire and brimstone.

Of course it wasn't long after the .460 WM's introduction before people began trying to "improve" it or utilize it for purposes other than smiting Elephants. Fred Wells is the first person known to have necked the .460 Weatherby Magnum up to .50 caliber. His wildcat cartridge became known as the .510 Wells and it caught the attention of J.D. Jones of SSK Industries. J.D. is of course well-known for his handgun hunting exploits, his line of proprietary Whisper cartridges, and his blunt no nonsense writing.

J.D. began experimenting with the .510 Wells with a military application in mind. However, as he worked with it he decided it wasn't quite what he was looking for. So, he set out to change the dimensions to better suite his needs and performance goals. The first thing he did was open up the throat of the reamer to enable it to handle .50 BMG projectiles. This would allow both .50-caliber hunting bullets and projectiles intended for use in the .50 BMG to be utilized. Next, he tightened the dimensions to improve case life.

The result of his handiwork will drive a 650-grain .50 BMG projectile at 2,400 fps from a short 23-inch barrel. Not only that but it will do it from a conventional 13-pound bolt action rifle. The cartridge is capable of using everything from the 750-grain A-MAX down to surplus 630-grain .50 BMG ball projectiles, and even lighter hunting bullets. Power wise it's similar to the old .5 Vickers (12.7x81mm) round. This obsolete English HMG round fired a 578-grain bullet at approximately 2,624 fps.

 When comparing the .50 Peacekeeper to the .50 BMG, barrel length needs to be kept in mind. While a .50 BMG M33 ball round may average 2,950 fps out of a Browning M2's long 45-inch barrel, results are less from shorter tubes. For instance, from a Barrett M82A1’s 29-inch barrel M33 ball velocity is a noticeably slower 2,735 fps. That is only about 335 fps faster than the .50 Peacekeeper when it’s fired from an even shorter 23-inch barrel. So, the .50 Peacekeeper is not too far behind the shorter barrel .50 BMG rifles.

So, just what was this round originally intended for? It was designed to facilitate a smaller and lighter anti-materiel rifle capable of putting the full range of .50 BMG projectiles on target. Things like helicopters, lightly armored vehicles, unarmored vehicles or other hard targets a .50 BMG rifle might be utilized for. For some situations J.D. felt that a conventional size and weight rifle would offer advantages over a much larger, heavier, and less mobile .50 BMG unit. Think about it, 80% of the power of a .50 BMG in a lightweight and easily portable rifle that to the casual observer outwardly resembles a conventional 7.62x51mm/.300 Win Mag Tactical rifle. Now throw in the fact that the ammunition is smaller and lighter, yet the projectile is the same. It can fire ball, AP, API, APIT or other types of loads. Kind of interesting, eh?

I had a chance to handle and test fire one of J.D.’s shop mules built on a Ruger M77 action in August 2002 and one built by Ed Brown in October 2002. Both were single-shots. The Ed Brown mounted a K&P Match barrel with cut rifling. Twist was one turn in 13 inches and the tapered barrel sported a simple, yet effective, 3.25-inch long muzzlebrake. This had four baffles to reduce recoil down to sane levels. The barreled action was bedded with Marine-Tex into a rugged McMillian A2 synthetic stock.

I tested the rifle off the bench and shot it offhand, kneeling, and prone. I utilized three handloads J.D. provided. These were topped with 650-grain API (Armor Piercing Incendiary) and APIT (Armor Piercing Incendiary Tracer) projectiles. Ed Brown provided a 700-grain AP (Armor Piercing) load. With an overall length of 45.6 inches and a weight of 13.5 pounds (with optics and bipod) the .50 Peacekeeper rifle simply felt like a normal heavy barrel tactical rifle. Balance was just in front of the receiver and the rifle felt good in the hands.

Recoil off the bench, especially with the 700-grain AP load, was attention getting. The Peacekeeper was physically moving me backwards some three inches with each pull of the trigger. This is NOT a rifle you want to creep the stock on. It's certainly not for everyone.  However, it didn’t have that quick painful flinch inducing jab of a lightweight magnum. Instead recoil was more like a hard shove that moves, but doesn't actually hurt you.

Accuracy with the military surplus projectiles was good, but I knew they were the limiting factor. Groups ranged from .75 to 1.5 inches depending on the load. Velocity averages ran from a low of 2,208 fps with the 700-grain AP load to a high of 2,402 fps with a 650-grain APIT. The 700-grain AP load averaged three inches for four three-shot groups fired prone at 400 yards. I fired one five-shot group at this distance and it measured 3.25 inches with four rounds in 1.5 inches.

The power is indeed impressive.  As an example I pounded a round at a steel plate 75 yards distant. The scope blurred, a ball of fire exploded on the ½-inch thick steel plate, and the APIT round pounded through it and a 5/8-inch thick steel plate behind it. While this wasn’t hardened armor plate, it was still impressive. Firing API and APIT loads onto steel targets proved great fun with visually impressive impacts.

Crunching some numbers, with Speer’s 647-grain FMJ-BT with a G1 BC of .701 and a muzzle velocity of 2,400 fps a .50 Peacekeeper’s performance was about 300 yards behind the same bullet fired from a 29-inch barreled .50 BMG at 2,750 fps. So, the .50 BMG had similar velocity and energy at 300 yards as the .50 Peacekeeper had at the muzzle. At 900 yards the .50 BMG load had similar retained velocity, energy and exterior ballistics to the .50 Peacekeeper at 600 yards and so forth.

While the US military was impressed by the .50 Peacekeeper they had a request. They wanted a detachable box magazine. Unfortunately, this was not possible using an existing off the shelf commercial action as it required too much metal being removed. Plus, the military had no intentions of paying for the R&D work to develop a new action. So, J.D. offered the .50 Peacekeeper to long range shooters and collectors. It didn’t catch on and today few have heard of this interesting .50-caliber cartridge.

Some will argue drones have reduced or eliminated the need for anti-materiel rifles, and perhaps they are correct. I found the .50 Peacekeeper very interesting when I had a chance to test it some 23 years ago. While it offered respectable performance, it never caught on commercially. Even so, it remains a fascinating cartridge from a very interesting man, J.D. Jones.

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