The YHM Model 57 Billet Carbine

By Christopher R. Bartocci

The AR business, like any other, has trends that alter the way the weapons are produced to make a more modern updated looking carbine instead of the legacy AR look going back to the early 1960s. Many companies have created unique looking receivers with a much more modern look such as AXTS, San Tan Tactical, Seekins Precision and now the Yankee Hill Machine Model 57. Providing to numerous OEM’s as well as manufacturers of their own weapons is Yankee Hill Machine Co., Inc. of Florence, Massachusetts. Opening their doors in 1951 as a job shop, Yankee Hill Machine (YHM) broke into the gun world in the late 1960s in the form of a government contract making cleaning kits. Around 1998, YHM started to sell complete AR-type rifles in co-op with ZM Weapons. The co-op dissolved and DPMS is now its own company. YHM has manufactured several weapon components for the U.S. military as well making them familiar with military grade quality control.

YHM manufactures a wide variety of components including rifle receivers, back up sights, front sights, rail systems, flash suppressors, lower receiver accessories as well as sound suppressors. They have a very good size selection of complete rifles ranging from entry level to professional. Along with their complete rifle line, they also sell complete upper receivers whether they are stock items or custom items. YHM has earned their reputation in this industry for quality and innovation. One does not have to look very far to see other manufacturers using YHM parts.

The newest entry to the market is the Model 57. To start with, the upper and lower receiver is manufactured from a billet instead of a forging. There are several reasons why this is a benefit over the forging. With a forging, there is very little that can be done to alter the look of the receiver without alteration of the forging die. Another big factor is when there is a buying surge of rifles and components forgings can be very hard to come by. Here in the U.S., there are relatively few forging companies that manufacture for the entire industry. These include Cardinal Forge, Anchor Harvey, Cerro Forge, Martin Marietta and Brass Aluminum Forgings, to mention a few. Many of these have U.S. government contracts with Colt and FN. In some cases receiver forgings that are rejected by those companies find their way into the commercial market as well. Basically, these are standard lower and flat top upper receiver forgings. YHM found during the frenzy of 2012 they had difficulty getting forgings. They wanted to be sure they could build rifles whether there were forgings or not.

Using a billet instead of a forging offers a starting point to allow the manufacturer to sculpture any design they like with the only limitations being the length and the width of the billet. Billets are also much easier to manufacture. The original YHM design arguably mimicked a forged lower (concept design started in January 2013). YHM started to make sure all of their specifications would match any upper throughout the industry. Although the design of their first six prototypes had a very unique look to them, it was too similar to that of a legacy lower so YHM decided on a course in a different direction. At this same time, the YHM engineering department had greatly increased in capability and innovation. YHM knew they could do vastly more with the lower with this new engineering approach as well as improve machining practices. Two more concepts later, YHM arrived with the current Model 57. Once the lower was completed, YHM decided on a whole package. Once this was decided, the YHM engineering team was challenged to come up with an entirely new rifle to show at SHOT Show 2014. By October 2013, YHM had their new billet upper receiver as well.

The Model 57 rifle has an unloaded weight of 7.43 pounds without a magazine. With the stock extended the overall length is 37.5 inches and with it closed is 33.5 inches. The rifle comes with two Magpul Gen 2 PMags and YHM Quick Deploy Q.D.S. sights, which are manufactured from 7075 T6 aircraft grade aluminum. The Model 57 can be purchased in 5.56mm, 300 AAC Blackout (7.62x35mm) and 6.8mm SPC calibers. Finishes are offered in flat black and burnt bronze. The MSRP is $2,195 for the flat black model.

Starting from the rear of the Model 57, the rifle uses a Magpul Commercial Specification CTR stock that is lightweight, durable and has a lock on the stock so it will not inadvertently move without intent. The receiver extension allows the stock six different positions.

The pistol grip is the Magpul MOE or Magpul Original Equipment. This is far more comfortable than the standard Mil-Spec A2 pistol grip and up more of the user’s hand.

The lower receiver is manufactured from a 7075 T6 aircraft grade aluminum billet, the same type of aluminum as the Mil-Spec forgings. The trigger guard is integral into the lower receiver and is oversized to allow for heavy gloves. The magazine well is cut in a unique shape and appears as though the front of the magazine well extends a little more than a standard legacy rifle. During testing of the T&E rifle it was found two magazines would not seat due to this. These were the H&K polymer magazine and the newly introduced Elite Tactical Systems translucent polymer magazines. This bears no reflection on the rifle; these magazines were designed a little different is all. The front of the magazine well has grooves machined into it making it easier and a more solid hold. The rear takedown and front pivot pins are the YHM designed E-Z Pull takedown pins that protrude from the right side of the rifle making field stripping of the rifle considerably easier and faster. The trigger is a two stage trigger that broke at 5 pounds

The upper receiver, also machined from a billet of 7075 T6 aircraft grade aluminum has a very unique sculptured look to it. Machined into the receiver is a forward assist as well as a fired cartridge case deflector. The ejection port has written on the outside the caliber and in the case of the T&E it said “5.56mm NATO.” All YHM firearms now include a caliber marked ejection port dust cover.

The barrel on the T&E rifle is a YHM manufactured 16 inch fluted barrel manufactured from 4140 steel and Melonite QPQ finished. The barrel is referred to as a ball cut barrel and is patterned in such a way so that although material is removed, it retains its original tensile strength. The rifle is offered with a carbine gas system. There are four different barrels offered by YHM: a standard 5.56mm Mil-Spec 1 turn in 7 inch barrel, a 5.56mm barrel with a 1 turn in 9 inch barrel, a 300 AAC Blackout/300 Whisper barrel with a 1 turn in 8 inch twist barrel to accommodate both super and subsonic loads, and a 1 turn in 10 inch 6.8mm SPC barrel. YHM’s ball cut barrel is at this time only available on complete Model 57 rifles. YHM offers both threaded and unthreaded muzzles as well.

The muzzle device was quite interesting called the YHM Slant Series Brake/Comp – a combination of a muzzle brake and compensator. The particular one on the rifle was the YHM-26-MB-A, which can also be bought separately for a MSRP of $70. This device stood out during testing as it did not have the brutal blast on the sides as you would come to expect from a muzzle brake and you could clearly feel it doing its job. Muzzle jump was negligible and although very uniquely and somewhat freaky looking, this muzzle device does an excellent job.

The handguard is the SLR (Slim, Light, Rail)-Slant Series handguard. The top of the rail makes a continuous top rail from the charging handle to the tip of the handguard at the muzzle end. The rail is T-marked so the operator will know the proper placement of the optics or other accessories to maintain zero. This rail is manufactured from 6061-T6 aluminum and is available in midlength as well as rifle length configurations. The rail on the T&E rifle is the midlength (YHM-5145), which has three QD mounts on the front left and right sides and the underside of the handguard. The rail is continuous on the top but the sides and bottom are only 3 inches in length on the front of the handguard. To the rear is smooth and very comfortable to hold. The 12 o’clock position of the handguard accepts customizable Mil-Std 1913 rails. The handguard is 2.18 inches wide and 2.18 inches tall. The handguard does require a proprietary barrel nut. All the necessary components and tools are provided with the handguard for installation. The handguard on the submitted T&E is their Specter Systems – a term coined by YHM that refers to a free floating handguard that extends over/past the gas system/gas block hiding it under the handguard. This also protects the gas system from any damage from the rifle being dropped or any other type of impact.

The rifle comes standard with the YHM Q.D.S. (Quick Deploy Sights) front and rear sights (YHM-5040). These folding backup sights feature a spring loaded automatic deploy system and lock positively in the upright and folded positions. They deploy by a spring loaded button and stow the same way. Both sights are manufactured from 6060-T6 aircraft grade aluminum. The rear sight has the same short and long range dual aperture as the standard A4/M4 rifles and windage is adjusted by a knob. No tools are necessary.

The bolt carrier group is standard Mil-Spec. The carrier group was very well machined and melonite coated. The charging handle has the new YHM tactical latch on it that makes it much easier to manipulate with gloved hands.

At the same time the new Model 57 arrived, so did some new magazines for testing manufactured by Hexmag. Product design of the Hexmag began in early 2013. Hexmag was incorporated in November of 2013 and began shipping product in March of 2014. The design was done by Adam Schefter, one of the company’s owners.

The material is very similar to other top end magazines that are made of a mix of nylon and fiber materials for strength. The magazine has a series of hexagram shapes on the magazine exterior. According to Hexmag, the grip is the number one benefit and they feel the design was more interesting to look at compared to what else is out there saying the pattern compliments the design and not distracts. The pattern saves on weight and they estimate the weight savings as two 5.56mm rounds per magazine.

Another outstanding feature of this product is the colored follower and the colored lock plate. The base plate has a hexagram shaped hole where the lock plate protrudes and locks the floor plate and magazine base together. No tool is needed to disassemble the magazine. One can use their finger to push inward on the lock plate and slide the floor plate off the magazine body. Both the follower and lock plate are offered in black, orange, green, red, yellow, pink and blue. By changing the color of the lock plate to various colors, this can help the shooter to identify caliber of the cartridges in the magazine as well as projectile types. The magazine itself is offered in black, Flat Dark Earth and olive green.

The market can expect other types of magazines in the future. Hexmag offers a Lifetime Warranty on their magazines. Prior to release, the magazines had been put through a battery of testing including drop testing and compatibility testing. The T&E magazines were subjected to different rifles as well as fully automatic fire.

The YHM Model 57 was tested with numerous magazines to determine compatibility. These magazines included GI aluminum, Magpul PMag, HK High Reliability steel magazine, Hera Arms polymer mag, Lancer AWM, Surefire 60-round and the new Hexmag. These all functioned without issue. The rifle was tested for function with 500 rounds of Black Hills Ammunition .223 Rem 55gr FMJ as well as Federal American Eagle .223 Rem 55gr FMJ. There were no malfunctions. The efficiency of the muzzle brake/compensator was quite noticeable on affecting muzzle jump. The feel of the handguard was quite comfortable. It was nice not having the rail at the rear of the handguard due to how uncomfortable that can be. The Magpul MOE pistol grip is always a winner. The best group shot that day was a .740 inch group by a SWAT Team sniper with Black Hills Ammunition MK262 Mod1 ammunition. This is a 77gr Open Tip Match Round used by SOCOM. It is this authors opinion this is the finest factory produced 5.56mm cartridge in the world. You get a combination of match accuracy and consistent wounding ballistics. Designed by Jeff Hoffman, this round has become the most sought after 5.56mm round in the military as well as foreign military who have had the chance to shoot it with their SOCOM advisors. Black Hills Ammunition makes this ammunition available to the commercial and LE markets as the 5.56mm 77gr OTM in their new manufactured ammunition line.

With all the variations of the Black Rifle you may be thinking, “Not another one!” This is not your typical copy of the M4 carbine – in fact it is the opposite. This rifle sports a new style upper and lower receiver, new free float handguard, excellent fluted barrel, advanced muzzle brake/compensator and more. The only thing this author would have liked to see different is that the gas block to be drilled and pinned in place instead of locked on with set screws.

This article first appeared in Small Arms Review V19N6 (July 2015)
and was posted online on May 22, 2015


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