USMC M40A5 Build- Part 1: Gathering the Parts

USMC M40A5 file — Texas - Staff Sgt. Ryan Dowling, a sniper with D Company, 4th Reconnaissance Battalion, 4th Marine Division, fires an M40A5 Sniper Rifle from high angles at unknown distance targets at greater than 1,000 yards during a simulated overseas firing scenario Sept. 24, 2014 at the High Angle Range, 9-Mile Training Center in Pecos County, Texas. Marine snipers from the 4th Mar. Div. conducted firing exercises that included known and unknown distance 7.62 mm training, night fire, unsupported positions firing, and a team stress shoot. Photo by Sgt. Paul Vinyard, courtesy USMC

To read Rifleshooter.com’s M40A5 Build Series, see:

Adopted by the United States Marine Corps in 2009, the M40A5 bolt action sniper rifle supersedes the M40A3 (both are still in use by active duty Marines). The Marine Corps is unique among the services since it actually builds its own sniper rifles.

Marines build their rifles at legendary Precision Weapons Section (PWS) in Quantico, Virginia. The Marines who craft these rifles have the Military Occupational Specialty (MOS) of 2112, Precision Weapons Repairer/Technician. If you read about Marine Corps built weapons, like the M40 series rifles or MEU/SOC pistols, you’ll often hear these technicians referred to as “2112s” (if you’d like to learn more about the USMC PWS, check out this excellent article from Small Arms Defense Journal).

Since I’m a former Jarhead that likes to build precision rifles, I’ve been tossing around the idea of cloning an M40A3 or M40A5 for the past 5 or 6 years. Thinking one day I’d build one, I’ve been hoarding information about the rifles from various sources by saving pictures, talking to 2112s, and interviewing the parts suppliers. Finally, I decided to pull the trigger and start gathering the pieces for my own project.

Building M40 clones is nothing new. Search Google and you’ll find various forum threads on rifles from all services, including the Marine’s M40A5. If you’ve never embarked on a project like this, the most challenging aspect is getting all of the correct parts. A great reference for this is TM 05539-IN, which is the Technical Manual for the M40A3 and M40A5. You can find a copy of it here.

A quick note, everything I’ll discuss here is freely and readily available on the internet. The M40A5 is essentially a customized Remington 700 in a McMillan stock. I’ll be knocking off 1960’s technology- no secrets are being disclosed (my grandfather was a tool and die maker and he could have built this from scratch 50 years years ago). While it would certainly be easier to just build a custom Remington 700 in 308 Winchester, that isn’t as fun as cloning an icon of the Marine Corps. In this case, the cloning is easy; buy the parts and assemble them to look like the pictures. Even easier, would be buying a complete M40A5 from a number of vendors, including C&H Precision Weapons Shop and GA Precision.

USS Kearsarge (LHD 3), At Sea, At Sea - U.S. Marines assigned to Scout Sniper Platoon, Weapons Company, Battalion Landing Team (BLT) 3/2, 26th Marine Expeditionary Unit (MEU), conduct a battlesight zero exercise on the flight deck of the USS Kearsarge (LHD 3), at sea, April 7, 2013. The 26th MEU is deployed to the 5th Fleet area of operations aboard the Kearsarge Amphibious Ready Group. The 26th MEU operates continuously across the globe, providing the president and unified combatant commanders with a forward-deployed, sea-based quick reaction force. The MEU is a Marine Air-Ground Task Force capable of conducting amphibious operations, crisis response and limited contingency operations. (U.S. Marine Corps photo by Lance Cpl. Juanenrique Owings/Released) — USS Kearsarge (LHD 3), At Sea, At Sea – U.S. Marines assigned to Scout Sniper Platoon, Weapons Company, Battalion Landing Team (BLT) 3/2, 26th Marine Expeditionary Unit (MEU), conduct a battlesight zero exercise on the flight deck of the USS Kearsarge (LHD 3), at sea, April 7, 2013. The 26th MEU is deployed to the 5th Fleet area of operations aboard the Kearsarge Amphibious Ready Group. The 26th MEU operates continuously across the globe, providing the president and unified combatant commanders with a forward-deployed, sea-based quick reaction force. The MEU is a Marine Air-Ground Task Force capable of conducting amphibious operations, crisis response and limited contingency operations. (U.S. Marine Corps photo by Lance Cpl. Juanenrique Owings/Released)

The good news about cloning the M40A5 and M40A3, is that most of the parts needed to build the rifle are currently in production. The M40A3 (after 2007), has all parts in common with the M40A5, with the exception of the Surefire brake (and suppressor) and PGW PVS-22 night vision optic mount (M40 Accessory Rail, although many M40A3s in the fleet now have the PGW mount installed, including pictures of those found in TM 05539-IN). So, if you want to build an post 2007 M40A3, the parts needed cost less than those for a M40A5.

Optics and accessories are a little trickier- but I’m not going to cover that here. For this post, we’ll look at the parts that I’ve gathered so far (the stock is on order from McMillan and I’m searching for a trigger).

PGW PVS-22 Mount

The PGW Defense Technologies Inc. M40 Accessory Rail (A-004/M40) is used in the M40A5 and later M40A3s. You can order it directly from the manufacturer PGW TDI (website is here).

Schneider USMC contract barrel

Schneider has the barrel contract for the M40A3 and M40A5 rifles. The barrel has a 6 groove 1-12″ twist and is made from stainless steel. Note the exterior finish of the barrel, it is fitted and installed with the tooling marks in place and isn’t ground or sanded to a fine finish. I was told by Gary Schneider the reason the USMC does this, is to hold spray paint used to camouflage the rifles in theater. Dave Clark at C&H PWS, former SNCOIC of the USMC PWS, confirmed this. The barrel is 25″ long when installed, 24″ from the front edge of the recoil lug (.925″ at the muzzle prior to brake installation). You can order USMC contract barrels directly from Schneider, click here.

Recoil Lug

The recoil lug is .312″ thick and made from pre-hardened tool steel. D.D. Ross has the original contract, however, I’ve heard from numerous sources that Badger Ordnance lugs are also used by the Marines. I’ll be using a Badger M40A3/A5 recoil lug (part number 306-01M) for my build. It is available from a number of online vendors. Mine came without oil and a little bit of surface rust (that is a quick fix).

Optical Platform (scope base)

The M40A3 and A5 both use a lugged, 30 MOA scope base, or optical mounting platform. The original contract base was made by D.D. Ross, however, he will not sell them. When I spoke to Ross, he told me that his contract does not allow him to sell these mounts. Badger Ordnance also makes M40A3/A5 mount that is almost identical to the Ross mount. I’ve been told by a couple of sources, that the Marines have used this mount on some of the current M40A5s. Since you can’t buy a D.D. Ross mount, I went with the next best thing and purchased a Badger mount. The Badger mount is part number 306-06-A3 and is available from a number of retailers online.

This base requires the receiver to be inletted for the optical platform’s mounting lugs. These cuts are known as “lug slotting”, and I’ll cover how this is done in a later post. If you plan on doing your own build, you’ll need a receiver cut for lug slots. If you don’t have a milling machine to do it yourself, Dave Clark offers this service. Clark is the co-owner of C&H Precision Weapons Shop located in Labelle, FL. C&H Precision Weapons Shop offers a wide variety of custom rifle building services, including clip and lug slotting. If you are looking to build a USMC rifle clone, he also builds complete M40A1, M40A3, and M40A5 rifles.

Jordan - A 26th Marine Expeditionary Unit (MEU) Maritime Raid Force Marine fires an M40 sniper rifle at a range in Jordan, June 19, 2013. Exercise Eager Lion 2013 is an annual, multinational exercise designed to strengthen military-to-military relationships and enhance security and stability in the region by responding to modern-day security scenarios. The 26th MEU is a Marine Air-Ground Task Force forward-deployed to the U.S. 5th Fleet area of responsibility aboard the Kearsarge Amphibious Ready Group serving as a sea-based, expeditionary crisis response force capable of conducting amphibious operations across the full range of military operations.(U.S. Marine Corps photograph by Sgt. Christopher Q. Stone, 26th MEU Combat Camera/Released) — Jordan – A 26th Marine Expeditionary Unit (MEU) Maritime Raid Force Marine fires an M40 sniper rifle at a range in Jordan, June 19, 2013. Exercise Eager Lion 2013 is an annual, multinational exercise designed to strengthen military-to-military relationships and enhance security and stability in the region by responding to modern-day security scenarios. The 26th MEU is a Marine Air-Ground Task Force forward-deployed to the U.S. 5th Fleet area of responsibility aboard the Kearsarge Amphibious Ready Group serving as a sea-based, expeditionary crisis response force capable of conducting amphibious operations across the full range of military operations.(U.S. Marine Corps photograph by Sgt. Christopher Q. Stone, 26th MEU Combat Camera/Released)

Badger Ordnance M5 detachable bottom metal

The Badger M5 detachable bottom metal is on the M40A3 (2007-2009) and the M40A5. It works well and is often copied by various other manufacturers. This is the easiest part to obtain, I ordered my Badger M5 bottom metal from Brownells.

Surefire Brake

M40A5s have two different options for a Surefire brake, both are correct. This is model CA762SSAL/RE and has a flash hider at the end. This model has been discontinued for some time and is hard to find. I bought mine used, from an online vendor. I didn’t want to use a brake since they aren’t allowed in F-Class competition (I plan on shooting my rifle in F-Class T/R- see rule 3.16.1).

Surefire’s MB762SSAL/RE brake (above) is also correct. Since it is a brake, it has baffles instead of slots like a flash hider. From what Surefire told me, this model has been discontinued. However, looking around online, it is still available from a number of vendors- which is good, it is a personal favorite. If you plan on building a M40A5, buy one now while you can.

Remington 700 Short Action Receiver

A Remington 700 short action receiver is used for both the M40A3 and M40A5. As stated above, the receiver needs to be lug slotted for the optical mount as shown above. I ordered my receiver from Brownells.

So what’s missing?

I am waiting for the McMillan A4 stock (just call and tell them you want one to USMC specifications) and searching for the trigger. A quick note on the McMillan stock, the cheek piece on the Marine Corps A4 stocks have two adjustment knobs. McMillan discontinued the two knob design for a single knob design. I confirmed with McMillan that the Marines never purchased a single knob cheek piece stock.

The correct trigger is a factory Remington, NSN: 1005015118314. These things are like hen’s teeth. Dave Clark suggested using a Timney 510. He told me it looks the same from outside and is a better trigger. I’ve used the Timney 510 quite a bit and am quite happy with it. If I can’t find the correct trigger, I’ll use the Timney as Dave suggests.

I’ll post again as my M40A5 build progresses. If you are looking at gathering parts for you or your gunsmith to build a rifle (if you need a gunsmith for your M40 build, I’d use C&H Precision Weapons Shop), I hope this has been helpful.

Trigger update:

I managed to get my hands on a real Remington M24 trigger (NSN: 1005015118314)!

This is the correct trigger for a M24, M40A3 or M40A5, and one of the parts needed for the upcoming M40A5 build. . Please see USMC M40A5 Build- Part 1: Gathering the Parts for more information on the project.

There aren’t many out there unless you want to pay a lot of money and I was fortunate enough to find one for a reasonable price.