American Built Arms Mod * X Chassis Stock + Trijicon’s AccuPower® Scope

By Chris A. Choat

The Remington 700 rifle has been around for more years than even this author can remember. If memory serves the rifle was introduced in the early 1960’s. Since then it has become the workhorse of bolt actions. The rifle is available in three different action sizes; the Short, Standard and the Long actions. These action sizes are related to the length of the cartridges that they fire. This author has owned one of the first Remington 700 SPS (Special Purpose Synthetic) tactical rifles ever since they were introduced. It is chambered in .308. It came with a very heavy H-S Precision stock and was marketed heavily to the military and law enforcement communities as the perfect sniper or counter sniper rifle. The rifle also features a heavy profile barrel. The barrel combined with the weight of the stock makes for a rifle that the user sure doesn’t want to pack around all day. The rifles’ weight did make it a very pleasant rifle to shoot, one that wouldn’t beat you up even firing several boxes of ammo during a range session. The rifle has an internal 4-shot magazine with a swing-down floorplate. Later in the rifle’s evolution Remington came out with a model that featured a detachable magazine.

This author’s rifle was and still is one of the most accurate rifles I have ever owned. With a good optic installed it is very capable of 1 MOA with just about any brand of ammunition. Recently I was sent a couple of New Products that proved to make this decades old Remington an even more accurate rifle as well as adding tactical features to bring it up to today’s military or LE standards.

The first product is made by a veteran formed and veteran owned company called A*B (American Built) Arms. Their product is an aluminum chassis called the MOD*X Modular Rifle System and is designed and engineered for military, law enforcement and even hunting enthusiasts. The A*B Arms MOD*X Modular Rifle System is a lightweight, ergonomic, drop-in platform for the Remington 700 Short Action. It serves as a modular foundation on which tactical accessories can be added according to the user’s needs.

The other product is one of Trijicon’s newest magnified optic the AccuPower® 4-16X50 riflescope. Trijicon has been making rugged military grade optics and sights since the early 1980’s. With the introduction of their first tritium powered red dot sight, the Armson OEG, they have been the company to look to for any kind of tritium powered red dot, scope or even iron sights. Their ACOG® line of optics have been chosen for use by military units the world over for their ruggedness. This author owns several of their optics and has never been let down by one.

These two new products arrived at this author’s office around the same time so they were destined to be combined into the same article. The Mod*X chassis system was installed on the author’s Remington SPS 700 short action .308 rifle. Installation is very easy and involves only removing your existing stock, in this case the heavyweight H-S Precision, and replacing it with the Mod*X chassis. The chassis is made from aluminum that is hard coat anodized to Mil-Spec Type III. The chassis comes in either black or flat dark earth. The sample sent for testing was black. The chassis weighs only 3 pounds 10 ounces and includes a 13.5 inch free-floating modular forearm that will accept even the heaviest custom contour barrel. The forearm has Key-Mod slots at the 3, 6 and 9 o’clock positions as well as conventional slots at the 11 and 1 o’clock positions. The author added a short KeyMod to Picatinny rail adapter to the bottom of the forearm for installation of a bipod. The company says that their product is made to provide “goof proof” installation. This proved to be exactly the case. Once the original stock is removed the main chassis “body” with attached stock mounting point is attached to the Remington 700 receiver using the supplied socket head screws. The chassis’ stock mount consists of a threaded block that will accept any AR style buffer tube. While any AR platform stock can be used on the MOD*X chassis it is shipped with the excellent LUTH-AR MBA (Modular Buttstock Assembly)-1 stock. This stock is fully adjustable for length of pull and cheek rest height. It weighs just slightly over 1 pound and can be used on any .223 or .308 AR platforms. Also included with the chassis is A*B Arms own P*Grip pistol grip. Here again, this modular chassis accepts any AR-15 style grip so if the user wants they can change it. While the P*Grip is a nice grip and even includes a storage compartment it proved to be just too small for this author's large hands and was replaced with a standard A2 pistol grip. The other parts of the MOD*X chassis system are the railed forearm and Picatinny scope mount. The forearm has a Picatinny rail that runs its entire length. The scope mount interlocks with the forearm with a steel alignment pin so the entire unit can be installed together. The forearm is held in place by two socket head screws that go through the chassis body and screw into the forearm itself. This makes for an extremely rigid setup. With the forearm installed and the scope mount installed into the forearm the scope mount is then attached to the rifle’s receiver by way of socket head screws that thread into the receiver’s drilled and tapped scope mounting holes. When it is all assembled it appears and feels as if it had been machined from one solid block of aluminum.

Did I mention that the MOD*X system also converts the host rifle to magazine feed? That’s right; the MOD*X chassis system allows the use of MDT and AICS-style magazines. One MDT 10-round polymer magazine comes with the kit. The magazine release is a small round button located inside the front of the trigger guard. The magazine seated very securely into the magazine well with no wobble or movement when locked in place. In fact, the mag needed a firm slap on its baseplate to lock it in. The magazine, when empty, dropped free of the magazine well which is a plus if a rapid reload is needed.

With the MOD*X installed it was time to mount the optic. The folks at Trijicon were nice enough to send a set of their 30mm steel scope rings along with the AccuPower scope. They were the perfect height for the 50mm objective lens to clear the MOD*X forearm. The MOD*X forearm and scope mount have 20 MOA built right into it. The AccuPower scope was then installed in the rings and the scopes’ reticle was leveled and plumbed. With everything tightened down, the scope was aligned with a laser bore sight just so it was “on the paper” at 100 yards.

The Trijicon AccuPower scope was their flagship 4-16X50 model. The AccuPower is a versatile, variable powered riflescope with an electronic illuminated reticle and 30mm main tube. Featuring a high quality lens system with full multi-layer coatings, the AccuPower provides an incredibly clear sight picture. The reticle illumination is powered by a single CR2032 lithium battery and has an easy-to-operate brightness adjustment dial with eleven brightness settings and an “off” feature between each setting. The AccuPower features a hard anodized aluminum body that protects against corrosion and is waterproof to ten feet (3m). With a generous adjustment range for windage and elevation, precise adjustment increments, and a re-settable zero, the AccuPower riflescope delivers the precision required for pinpoint accuracy. The test scope featured the Mil-Square reticle with red illumination. Green illumination is also available. The MIL-Square reticle was designed by a former Marine Sniper to give a shooter refined aiming points compared to the widely accepted MIL-Dot. This reticle provides the capability of determining distance to a target, determining the size of a target and to provide visual reference points to be used to compensate for bullet drop and provide reference for follow up shot compensation. Because of the open square (instead of mil-dot) design the user can more accurately align the edge of the MIL-Square with the edge of the object being measured. Intermediate tick marks aid in increased accuracy for ranging or shot placement.

With the chassis and optic mounted to the rifle it was time to head to the range. A Harris bipod was mounted to the short section of rail on the forearms bottom. All shooting was done either in the prone position or from a shooting table. Ammunition used included Gorilla Ammunition’s .308 WIN 175 grain Sierra MatchKing©, Federal Premium .308 WIN 180 grain Nosler Partition, Hornady .308 WIN 168 grain TAP and Beck Ammunition .308 WIN 168 grain A-Max Subsonic, for use with a suppressor, but more on that later.

The author has owned the Remington 700 used in this test for over 20 years and it has proven to be deadly accurate. In fact, this author didn’t think that the rifle could be more accurate than it already was. These two new products proved me wrong. Instead of a 1 MOA rifle with the MOD*X installed along with the Trijicon AccuPower the gun is now a ½ MOA rifle. All groups shot with the rifle shrank in size. We had several 3-shot groups, fired at 100 yards, that looked like small cloverleafs. The ammunition used in the test was also shot through the rifle before its “transformation”. Almost all group sizes dropped by at least half. Some were even more than that. The supplied magazine fed all of the test ammunition perfectly regardless of bullet style.

Several years ago I had the barrel of this rifle shortened and threaded for suppressor use. A Thompson Machine “Thirty” suppressor was installed and shot using the Beck Ammunition .308 WIN 208 grain Subsonic ammunition. If you have a .308 rifle and a suppressor for it you have to try this ammunition. It is the ultimate in quiet. You can hear the bullets impacting the target. Beck Ammunition also makes a subsonic load with a 168 grain A-Max bullet and well as several .223/5.56 subsonic loads in several bullet weights.

In conclusion, if you have a tired old Remington 700 or even a brand new, right out of the box, gun you can bring it into the 21st Century with the MOD*X Modular Rifle System. You get the advantages of a lighter weight gun that will shoot more accurately as well as the addition of the KeyMod and conventional slots for mounting any accessory that you can think of. With the addition of a full-length Picatinny rail you also have plenty of rail real estate for the mounting of night vision optics along with your regular magnified optic.

In regard to the AccuPower, this author has always been a fan of anything made by Trijicon and this scope proved to be no exception. It is rugged, repeatedly accurate and one of the clearest optics I have ever used. The Mil-Square reticle coupled with the illumination proved invaluable in ranging and usability even in low-light situations. I may even have to buy this scope instead of sending it back after the test. I have become quite
attached to it.

A*B Arms


Beck Ammunition

This article first appeared in Small Arms Review V20N2 (March 2016)
and was posted online on January 22, 2016


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