Torture Test: U.S. Ordnance MAG-58/M240

Torture Test: U.S. Ordnance MAG-58/M240

We’ve already mentioned the capabilities that U.S. Ordnance has at their facility. It’s necessary when supplying military grade firearms to stick to a specification for manufacturing process. However, there will be certain procedures that can be changed to produce a more durable product, as long as the R&D and production teams know what the issues involved downstream are.

One of the most important changes that U.S. Ordnance has made to their design, beyond the full induction heat treatment of the locking lugs, is the inner rail that needs to be riveted to the sideplate. This can be a problem area and U.S. Ordnance programmed their mills to build that into production of the plate instead of needing to rivet it in place. This strengthens the area of the rail and streamlines the process.

As mentioned elsewhere, U.S. Ordnance wanted to ensure full compatibility with all mounts and accessories. Shown in the picture is the U.S. Ordnance M240 with U.S. M240D spade grips, on the famous Belgian 360° softmount tripod. The thorough testing with other parts showed no issues. It’s interesting to note that U.S. Ordnance had received requests to make M240C (right hand feed) top covers with a Picatinny rail on them. Typically the “C” guns are fixed, but in the Afghanistan and Iraq conflicts, twin M240s on a variety of mounts have been used. Some mounts use two standard M240s, left hand feed, and if they are needed in the dismounted role, they can have an optic on the rail. In the case of tighter mount construction that uses a right hand feed top cover, dismounting loses the optic capability. This solves a number of issues for special users, and U.S. Ordnance has the capability to adapt to this.

Our last, and perhaps one of the most important questions: Will the parts from the U.S. Ord M240 interchange with what’s currently in a country’s inventory for MAG series weapons?

The last test we needed to fulfill was parts inter-changeability with the other models on the market- after all, the MAG-58 series of machine guns has been on the scene for over half a century. Many potential customers would already have a MAG-58 variant in their inventory, making it imperative that they know what will interchange and mesh into their existing structure. There are differences in feeding between calibers such as the early KSP-58 guns, which are no longer on the market and were only used by Sweden, and then there is the current use of either non-disintegrating metallic belts or the M13 disintegrating metallic link, but the latter is easily addressed by changes in the feed tray, in a well-known manner. It’s easy enough to accommodate the customer on which belt system they want to use. We brought the test gun to LMO’s facility in Henderson, and went into the classroom for a thorough comparison of variants found in most modern arsenals.

(MAG-58) The first that we tested changing parts was with the standard Belgian FN MAG-58. There were no problems at all, it was a 100% interchange, full functionality. Starting with the MAG-58 type from U.S. Ordnance, everything meshed perfectly. U.S. Ordnance does have a different retaining pin style in their top cover, preferring the straight pin with split end to the curved one with bend, but that’s just a preference.

Lined up in LMO’s training room are the basic MAG-58 descendants that were used in the parts interchange and replacement test. Front to rear: U.S. Ordnance’s M240, Belgian MAG-58, U.S. M240B, British L7A2 “GPMG,” Israeli MAG-58. On the front of the table are a set of M240D spade grips and trigger assembly. Not Shown- Indian MAG-58. (Photo by Dan Shea, courtesy LMO Working Reference Collection.)

(M240B) On the U.S. M240B, it’s a different gas regulator type, and that’s an easy fix; just how you prepare the barrel in your order. Bravo heat guards interchanged, and the rail top covers were exact. The Bravo guns use an hydraulic buffer in the stock as opposed to the mechanical one from the MAG, but U.S. Ordnance says they can accommodate any customer who needs the hydraulic buffer stock.

(L7 series) We checked a number of the British “Jimpy” (GPMG) variants and all had the barrel differences- you can’t interchange the British barrels with anyone else, the gas tube has a different profile and the barrel has partial arc ridges on it that keep them from being used by other types. U.S. Ordnance can accommodate this quite easily.

(Israeli MAG-58) This is a basic MAG-58 with some differences in stock profile and sights. As such, the parts interchanged all the way through the weapon system other than the sight location on the barrel, which is further back, and the stock profile. U.S. Ordnance says they can accommodate any customer that needs this type of setup, but if it’s not important, their regular stock and sight/barrel assemblies work.

(Indian M2) The Indian manufactured “M2” is a MAG-58 tank style gun- the M240 coax. As such, all of the internals and regular parts fit, so the “M2” can be converted to regular ground gun style using U.S. Ordnance parts.

The end result on the compatibility interchange? Passed with flying colors. After discussions with U.S. Ordnance personnel, we were absolutely satisfied they could improvise, overcome and adapt to almost any scenario the customer can have. Aircraft sights? Yes. Spade grips? Yes. We tested with U.S. and Belgian Spade grips, no problems at all. Right hand feed? U.S. Ordnance is even making them with a rail top cover- for twin mounts. They were aware of the many variants in the world today, and were clearly prepared to address the customers’ needs.

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U.S. Ordnance
TEL: 775.343.1320
FAX: 775.343.1331


300 Sydney Drive
McCarran, NV 89434

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