Ohio Ordnance Works M240 SLR

posted on April 14, 2011

Introduced in 1957, the Mitrailleuse d`Appui Général (MAG) designed by Fabrique Nationale’s Ernest Vervier, quickly became the most widespread general purpose machine gun of the post-war era. It was belatedly accepted by the U.S. military first as a coaxial tank gun, then by the U.S. Army and Marine Corps for infantry use as the M240B and M240G, respectively, in the mid 1990s. The gas-operated, air-cooled M240 essentially uses the feed system of the MG42, the riveted receiver construction of the Browning medium machine guns, and the bolt of the Browning Automatic Rifle, although the latter component locks into the receiver’s bottom rather than the top.

Relatively few fully transferable MAGs are in civilian hands, and the cost of a transferable MAG of any sort is upward of $70,000. Ohio Ordnance Works (OOW) is offering a semi-automatic-only version of the M240 as its M240 SLR (for self-loading rifle).

The M240 SLR is a mix of original M240 components and parts designed and manufactured by OOW. The right sideplate, which is the receiver according to the BATFE, is thicker than the military M240 and the interior parts have been reduced accordingly to ensure that fully automatic components cannot be inserted. Further, the SLR cannot accept a military trigger group or operating rod.

The OOW gun, except for its markings is externally identical the military M240. But the M240 is a machine gun that fires from an open bolt, and OOW’s Bob Landis redesigned the fire control group to function as a semi-automatic-only, closed-bolt-operated gun. The recoil spring, which is behind the bolt group on the military M240, was cleverly moved to the interior of the gas piston. Moving the recoil spring allowed OOW to add a new in-line hammer to the rear of the bolt group. Powered by a heavy coil spring, the hammer moves on the guide rails for the bolt link assembly. After being tripped by the sear, the hammer moves forward to impact a striker mounted in the rear of the bolt link, then the energy is transmitted to a transfer pin in the operating rod, and, finally, to the rear of the firing pin. All three components must be perfectly aligned and locked in order for the firing pin to be struck.

Landis also developed a new semi-automatic-only, two-stage trigger group for the SLR, and it includes a trigger- and sear-blocking safety on the top rear of the pistol grip. It is engaged by pressing it from left to right. When in the “fire” position a red “F” is visible on its rear.

Like its military cousin, the OOW M240 SLR feeds from a belt of M13-linked 7.62x51 mm NATO or .308 Win. cartridges. To load, depress the dual top cover latches and lift up the rear of the cover, exposing the feed tray. Insert a belt of linked cartridges from the right side with the open part of the links facing downward with the first cartridge firmly against the cartridge stop, then close the top cover. Retract the charging handle on the right side of the receiver and let it go forward, chambering a round. The gun is then ready to fire. Ejection of spent cartridge cases is through a port in the Parkerized steel receiver’s underside

After a cartridge is fired, gas bled from a port in the barrel’s underside passes into a one-position gas regulator, then into the gas tube, driving the operating rod rearward. The bolt assembly is attached to the operating rod via a link assembly. As the rod moves rearward, the bolt is unlocked from its recess in the bottom of the receiver and moves rearward for extraction and ejection. As the bolt returns to battery, a fresh cartridge is stripped off the feedway and into the chamber. A spring-loaded roller on the bolt carrier’s top matches up with a cam track on the feed tray’s underside, placing the feed mechanism in position to index a cartridge for the bolt to strip into the chamber.

The stout 20-inch long barrel tapers in diameter from 1.83 inches to 0.90 inches at its thinnest point, and is topped with a birdcage flash hider. The barrel assembly comes with an issue heat shield as well as a block with two strips of Picatinny rail on either side of the barrel. Depressing the release on the receiver’s left side frees the quick-change barrel for removal. The barrel is retained in its trunnion by interrupted threads that rotate 90 degrees and allow the barrel and regulator assembly to be removed.

The blade front sight is adjustable for elevation and is protected by stout ears. An aperture battle sight allows adjustments from 200 to 800 meters by sliding the elevator. Machined into the aluminum top cover is 7 inches of M1913 Picatinny rail for the attachment of optics.

We fired more than 600 rounds in the course of our function and accuracy testing of the SLR, with a mixed bag of 7.62x51 mm NATO and .308 Win. Ammunition, and there were no malfunctions. A Leupold Mk 4 3.5-10X 40 mm in Leupold Tactical rings was mounted to the top cover’s Picatinny rail for accuracy testing. The shooting evaluation was from the prone position using the rifle’s stamped steel bipod with a sandbag under the butt. For function firing a Trijicon Reflex sight was added. Despite its 5-pound, 8-ounce trigger pull, the M240 SLR proved extremely accurate, particularly with Federal Gold Medal Match. Recoil was negligible, and the rifle was extremely fun to shoot, especially at 300-yard targets using the Trijicon.

At more than 24 pounds, and costing $13,500, the rifle is neither small nor inexpensive. Admittedly, the OOW M240 SLR is the most expensive gun we have tested in some time. One might complain about the price, but not about the quality or the accuracy.

Manufacturer: Ohio Ordnance Works, Inc.; (440) 285-3481; www.ohioordnanceworks.com
Mechanism Type: gas-operated, semi-automatic center-fire rifle
Caliber: 7.62x51 mm NATO (.308 Win.)
Overall Length: 47 5⁄8"
Barrel Length: 20"
Weight: 24 lbs., 6 ozs.
Feed System: M13 disintegrating link
Rifling: four-groove; 1:12" RH twist
Trigger Pull: two-stage, 5 lbs., 8 ozs.
Sights: blade front adjustable for windage and elevation, ladder rear adjustable for elevation, M1913 Picatinny rail
Stock: black synthetic: length of pull, 14 1⁄8"; drop at heel, 1 5⁄8"; rise at comb, 1¼"
Accessories: manual, sling, cleaning kit, disassembly tools 2,500 M13 links, ruptured case extractor, gas regulator cleaning tool, Pelican hard case
Price: $13,500


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