USMC M40A3
An Upgraded Sniper System?

23 July 2002
By Mike Miller

Many have heard the United States Marine Corp is fielding new sniper system but few have tested one. I have been testing a M40A3 for the last twelve months. NorCal Precision and GA Precision built the rifle in this article in combination. NorCal did the action/bbl and bedding work. GA Precision did the clip slotting and applied the finish to the metal. Either company is capable of building a M40A3 to USMC Specifications. This article is the result of hundreds of hours working with the system and many more talking to the persons responsible for design and the end users. Since the author had nothing to do with the design there was no bias before starting this project. I went into this with a completely open mind.

The first sniper rifle I ever used was the M40A1 and that was over twenty years ago. The original rifle served me well for many years until a new one was built by NORCAL Precision, in the San Francisco Bay Area, about four years ago. That rifle was built with a McMillan A4, the same stock as what's used on the USMC M40A3. I like the stock design so I was glad to see it used here.

The rest of the components are as follows

The barrel is a Schneider and cut to 24" from the recoil lug to the muzzle. This is a change from how barrels are normally measured and really should be called a 25" barrel. The contour is fairly described as a typical sniper contour and just about the same as the original M40A1 barrel. The twist is 1x12". This is a fine barrel and as good as any you could get period. The length of the barrel was determined after the USMC Precision Weapons Shop did extensive accuracy, velocity and flash suppression testing. Reports from the testing indicate the average life of the Schneider barrel to be over 10,000 rounds and still holding minute of angle groups at 300 yards. A finer barrel can not be found.

The floor metal is provided by the DD Ross Company. It is tough and well made. This is a substantial improvement over the original modified Winchester steel floor plate used on the M40A1. This improvement comes with a price tag of nearly double the weight. Since the original floor metal never had a serious problem of being weak I wonder why the added weight issue was not looked at. For a police rifle, where you don't have to carry your equipment for days it would not be an issue but for a field sniper, every extra once of equipment is one less ounce of water or ammunition you can carry. Everything adds up. For the same amount of weight the use of an HS Precision Detachable magazine system could have been used. This system would allow rapid magazine changes of either four or ten rounds. I talked with the designers of the M40A3 system and they felt the DD Ross was more durable so they went with it. Once again it's a trade off the ultimate in durability versus quick magazine changes. I see a good reason for both.

The receiver is a Remington Short Action Model 700. The action has been trued, at the USMC Performance Weapons Shop. They have been building sniper rifles for decades and the work is outstanding. They barrel and chamber the action, using a heavy recoil lug. The Remington 700 action is the current standard for most top grade sniper weapons.

As said earlier the stock is the McMillan A4. It is fully adjustable for comb height and length of pull. The rear of the stock has a hooked area perfect for prone shooting. The fore stock is square, stocky and my only area of complaint. The fore stock adds about a pound to the stock and does not allow for easy elevation like the McMillan A3 does. The stock would be easier to carry and use if the fore stock design was changed to the A3 design. This would take off about a pound and make it more useable in the field. The A3 forend is angled so height adjustment can be made by sliding the rifle to the front or rear on sand bags. The comb height is adjustable by the use of an aluminum cheek piece. This is my only other complaint about the stock. It is heavy and provides far more adjustment than needed. I removed this and replaced it with an Eagle Stock Pad. The systems weight was reduced by nearly half a pound by the change to the stock pad. Another choice, not available to the USMC at the time of the initial testing but since to hit the market, is the McMillan built Sub minute Solutions Stock. This is nothing more than the original M40A1 stock with adjustable comb and length of pull features added. This stock is about one and one half pounds lighter than the A4 stock. It may be tested at a latter date.

The stock is bedded to the action in an almost Bench Rest fashion. The action and floor metal are bedded using epoxy resin, with pillars between. It is neatly done but unlike every other sniper rifle maker who uses epoxy resin, the USMC did not bed the recoil lug or provide a barrel pad just in front of the recoil lug. Talking with the designers I was told this was so stocks could be switched in the field without bedding. This allows them to start with a hand built weapon that gets every ounce of accuracy and if something goes wrong it is then very much like the US Army's M24 system without being tightly bedded. The latter relies on torque to keep accuracy consistent. The torque system also works very well. My experience with completely bedded rifles is they will hold between 1/4 and 1/2moa while the rifles that rely on torque and bedding blocks will hold about 1 1/4moa more. In this case I tried the M40A3 rifle in an HS Stock and only lost about 1/4moa in the accuracy department. While the M40A3 would hold 1/4 moa groups out to 600 yards, the HS Stocked (non-bedded) would hold 1/2moa groups to 600 yards. It's a trade off, more accuracy for far more work. The HS System bolts-in in seconds while a bedded stock takes about two days of drying and four hours' work. Bedding is more accurate but non-bedded is more field ready.

The scope base, provided by DD Ross Company, is of the best quality. It mounts by four 8-40 screws and clip slots front and rear into the receiver. It is a very secure mount. The base has 30 Minutes Of Downward Angle machined into it. What that means is the scope with the erector centered will be 30 inches high at 100 yards and will need to be adjusted 30 minutes of angle down to be point of aim point of impact at 100 yards. The common scope base angles for long range 308 Winchester shooting is either a 15 or 20 moa base. When the M40A3 for the article was being built I could not get the issue base in time for initial testing so I contacted Badger Ordnance for a substitute. Badger makes a base that also mounts in the dual clip slot fashion. The Badger is of equal quality and available.

Talking with the Badger owner, Marty Bordson, I was told that he thought 30 minutes built into a base would be more than most Bullet Drop Compensation Scopes could adjust for. He proved correct. I could not get a workable 100 yard zero with a Leupold MK4 M3 or some of the original M40A1 scopes. With manufacturing tolerance being what they are not all the original scopes would adjust down that far. Since the rifle is to be used with the M40A1 Scope, you would think this was a huge problem, but the USMC had reasons for the 30 moa base. They were also testing a Night Vision Device that needed the 30 MOA base for extreme range shooting. The USMC turned to US Optics for a solution. US Optics has the contract for repair of all the original M40A1 scopes. US Optics was able to make a small change in the original scopes that allowed the original scopes to work perfectly on the 30moa base. The fix is included in the normal refurbishing of the scopes so no additional cost or down time has been suffered.

The scope rings are Badger Ordinance brand. The front ring is wider than the rear. This is for a special cap that provides a mounting platform for the SIMRAD Night Vision Device. This device allows the user to use a day scope and attach a NVD over the top and slightly in front of it. A great idea but a change of zero does occur. In defense of the system the change is repeatable so you can allow for it. It certainly beats changing from a day scope to a night scope and is a better choice than using a combination Day/Night scope. My experience with day/night scopes is they don't provide the best day or night scope available. To quote someone long gone "Multi-purpose means good for nothing". One day someone will perfect this, but it's the author's opinion we are not there yet.

The scope for the final issue has not been decided. The rifles in the field have the M40A1 Scope on top. After talking to the designers and end users it appears the options are down to a choice between a variable power day scope and a day night scope called the PVNS 10. Talking with USMC Sniper Schools at Camp Pendleton CA the PVNS10 Day/Night Scope is well liked followed closely by a US Optics Variable 1.8-10x44mm, 30mm tube with M40A1 BDC System Scope. Tests of the PVNS-10 were done with mixed feelings. It was a fair day scope and a good night scope. Daytime optics is not close to the quality of the US Optics Variable, mentioned above, that was also tested. The US Army Special Forces has been using the PVNS-10 for longer than the USMC has been testing it, so the Special Operations Interdiction School (Special Forces Sniper School) was contacted and asked for an opinion. Now the opinion is of an instructor who has been in the sniper business for over twenty years but not the official US Army Position. The opinion was that "They should stay with a good day scope and the SIMRAD is already in supply." Cost will also become an issue as you can buy five Day scopes for the price of one PVNS-10. Short opinion, keep the SIMRAD and pick a good day scope. The reason for going to a variable power scope is the increasing call for police type actions by the USMC in urban areas. This means closer and moving targets. With lower power you get wider field of view.

We tested the US Optics SN3 Variable 1.8-10x44 and found it tough and the clearest lenses tested to date. This scope is adjustable for parallax. The parallax adjustment is on the front objective. At first I thought this would be a problem but found with the scope's size and the position of the adjustment it was no more cumbersome to adjust than the side parallax adjustment models currently the rage. It is easy to do without changing your position or losing your site picture/cheek weld. The knob/BDC system used works, looks and adjusts like the original M40A1 scopes do. You either love it or hate it. Years of crawling, with sniper rifles has taught me to keep things simple and tough. This system is simple, durable and easy to use. It is caliber specific but just plain works well.

The rifle is capable of surgical precision shooting. In a Hostage Rescue Operation it would be the first rifle I would pick to hit a quarter-sized target at 300 yards. Handling the weapon you will notice its heavy at about 17lbs with scope and Harris bipod. That's a bunch and may prove to hurt extended operations. The original M40A1 is about 14lbs rigged the same way. As said before the more a weapon weighs the less ammo and water a sniper can carry. The weight is my only complaint about the rifle. Tests were done to see if the weight could be lowered and the accuracy kept the same.

First was to substitute a fully adjustable HS Precision stock for the McMillan A4. This saved about a pound but the groups opened up 1/4moa more than with the McMillan Bedded A4.

Next was changing the floor metal to an HS Precision detachable magazine steel floor plate. Lost about a forth of a pound, no loss in accuracy. Picked up the ability to have quick magazine changes and four or ten round capacity. This is a very nice feature.

Next was changing the McMillan A4 stock for a recently designed stock. The stock is made for Sub minute Solutions Company, by McMillan Fiberglass Stocks. It is basically a M40A1 stock with a wheel adjustable comb and stock spacers. In all fairness this stock was not available when the M40A3 was designed. With the Sub minute Solutions Stock, bedded, no loss of accuracy was seen. It cut the weight down by approximately a pound.

In all we were able to cut the weight down by only a pound and a third, down to about fifteen and one half pounds. The only way to lessen the weight more would be to cut the length of the barrel, flute the barrel or decrease the diameter of the barrel. If the USMC were to decrease the diameter to the same size as a Remington Police Sniper Rifle and flute it, the weight would be reduced by about two pounds more. In short the same basic rifle would weigh between thirteen and fifteen pounds depending on the stock, floor metal and barrel contour picked. My current favorite field rifle is a GA Precision built rifle they call "The Rock". It's similar to the M40A1 but with a fluted 22" barrel. It is capable, with Black hills brand 175-grain 308 Winchester ammunition, to hit man sized targets at 1000 yards. This rifle weighs twelve pounds with an US Optics SN3 scope. Compared to the M40A3, The Rock is far more user friendly to carry great distances.

In short the M40A3 is one of the most accurate rifles I have ever tested but the weight is several pounds more than a sniper should be expected to carry in the field.


For further information contact:

US Optics 714-994-4901
NorCal Precision 707-552-3810
GA Precision 816-221-1844
DD Ross Company 330-725-3032
McMillan Fiberglass Stocks 623-582-9635



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