M40A3
Historically Faithful Reproduction of the U.S. Marine Corps M40A3 Sniper Rifle
The B&B Firearms M40A3 recreates one of the most recognizable evolutions of the legendary Marine Corps M40 rifle.
Developed as the successor to the M40A1, the M40A3 retained the proven Remington 700 short-action foundation while introducing a heavier Schneider match barrel, the distinctive McMillan A4 fiberglass stock, an adjustable cheekpiece, adjustable length of pull, improved sling mounting and a modernized optics mounting system.
Built around original-pattern components and specifications, the B&B M40A3 is intended for collectors and shooters looking for a historically faithful reproduction of the M40A3 sniper rifle rather than a modern precision rifle that simply resembles one.
Built to Order
Estimated Lead Time: 6–8 Weeks
The History of the M40A3
The lineage of the M40A3 traces directly back to the original Marine Corps M40 adopted during the Vietnam War.
For decades, the M40A1 served as the standard bolt-action precision rifle of Marine Corps Scout Snipers. By the 1990s, however, improvements in stock design, optics and precision-rifle components created an opportunity to modernize the M40 platform without abandoning the Remington 700 action that had formed its foundation since 1966.
The result was the M40A3.
The M40A3 represented a substantial evolution of the M40 rifle while maintaining the basic philosophy that had defined the platform: a proven bolt action, a heavy match barrel and a rifle individually configured for precision use.
One of the most significant changes was the adoption of the McMillan A4 fiberglass stock. Compared with the comparatively simple M40A1 stock, the A4 added an adjustable saddle cheekpiece, spacer-adjustable length of pull, multiple flush-cup sling attachment points and a more substantial vertical-grip profile.
McMillan specifically developed the M40A3 stock for the Marine Corps Scout Sniper program and continues to manufacture an M40A3-specific A4 configuration today.
The M40A3 also standardized the use of Schneider match-grade stainless-steel barrels. Schneider states that it was the qualified barrel supplier for the Marine Corps M40A3 and subsequent M40A-series rifles and that the A3, A5 and A6 shared the same basic barrel contour while being finished to different lengths.
The early M40A3 retained a traditional five-round internal magazine and hinged floorplate arrangement. The original M40A3 bottom-metal configuration used a D.D. Ross-style steel assembly, preserving the traditional internal-magazine architecture of the M40A1 while providing purpose-built hardware for the new rifle.
Later in its service life, some M40A3 rifles were upgraded with detachable-magazine systems and newer optics, helping establish features that would eventually become standard on the M40A5.
The M40A3 saw extensive service during the early 2000s and became closely associated with Marine Corps Scout Snipers during operations in Iraq and Afghanistan. An official Marine Corps account from 2006 describes Scout Snipers continuing to field the bolt-action M40A3 while the Corps introduced the semiautomatic Mk11 alongside it.
Today, the M40A3 remains one of the most recognizable rifles in the history of the Marine Corps sniper program and an important link between the classic M40A1 and the later M40A5.
B&B Firearms M40A3
The B&B Firearms M40A3 is built to preserve the defining characteristics of the original M40A3 sniper rifle.
Rather than placing a Remington-pattern action into a generic tactical stock, the rifle is configured around the components and dimensions associated with the original Marine Corps weapon system.
The result is a newly manufactured rifle built for customers who appreciate the small details that separate a serious M40A3 reproduction from an M40-inspired precision rifle.
M40A3 Specifications
Action
Remington Model 700 Short Action
The M40A3 continued the Remington 700 short-action architecture used throughout the M40 family.
Action: Remington Model 700
Action Length: Short Action
Action Type: Bolt Action
Orientation: Right Hand
Bolt Face: Standard .308 / 7.62 NATO
Historical Receiver Configuration: M40-pattern receiver machining
Recoil Lug: .312" M40A3-pattern recoil lug
PTG identifies the heavier .312-inch recoil lug as the M40A3/M40A5 specification and currently offers Remington 700 short actions with M40-specific machining.
Barrel
Schneider M40A3 Match Barrel
The M40A3 uses a heavy Schneider match-grade stainless-steel barrel.
Schneider states that it supplied the barrels used on the Marine Corps M40A3 and later M40-series rifles. Its M40 barrels are manufactured from stainless steel, button rifled, stress relieved, contoured and individually hand lapped.
Manufacturer: Schneider Rifle Barrels
Chambering: .308 Winchester / 7.62×51mm NATO
Material: Match-grade stainless steel
Contour: #7 Schneider / M40 heavy contour
Twist: 1:12" RH
Muzzle: Recessed precision crown
Muzzle Brake: None in original M40A3 configuration
Suppressor Mount: None in original M40A3 configuration
Finish: Subdued matte-black appearance
McMillan's current USMC-spec M40A3 stock is specifically inlet for the #7 Schneider barrel contour, confirming the barrel profile associated with the original rifle.
Stock
McMillan A4 M40A3 Stock
The distinctive McMillan A4 is one of the defining features of the M40A3.
McMillan developed the stock specifically for the Marine Corps Scout Sniper program and still offers an M40A3-specific version using the original-style Olive Green molded-in fiberglass construction.
Manufacturer: McMillan
Model: A4 / M40A3
Construction: Fiberglass
Fill: Sniper Fill
Color: Molded-In Olive Green
Action Inlet: Remington 700 Short Action
Barrel Inlet: #7 Schneider / M40 contour
Cheekpiece: Gen 1 Adjustable Saddle
Adjustment: Dual-knob
Length of Pull: Spacer adjustable
LOP Range: Approximately 13"–14.5"
Front Sling Stud: 1
Flush-Cup Mounts: 6
Left Side: 2
Right Side: 2
Bottom: 2
Approximate Stock Weight: 4.75 lb.
McMillan notes that the earliest M40A3 stocks used a deeper, more forward butt hook. After roughly the first 100–150 stocks, the design was revised with a smaller hook positioned closer to the pistol grip. Both configurations are historically genuine M40A3 patterns.
Trigger
Remington-Pattern Precision Trigger
The M40A3 retained the traditional Remington-pattern trigger architecture used throughout the earlier M40 family.
Trigger Type: Single Stage
Pattern: Remington
Safety: Receiver-Mounted Remington Pattern
Configuration: Precision-adjusted for the rifle
The M40A3 did not require a modern modular trigger system; its fire-control layout remained fundamentally tied to the Remington 700 action.
Bottom Metal
USMC M40A3 D.D. Ross-Pattern Hinged Floorplate
The original M40A3 retained a traditional internal magazine rather than a detachable box magazine.
The historically correct configuration uses the D.D. Ross-style steel trigger guard and hinged floorplate assembly.
PTG currently manufactures an M40A3 trigger guard from original USMC M40A3 prints, using ordnance-grade steel and an inlet compatible with the D.D. Ross-pattern stock.
Configuration: Hinged Floorplate
Material: Ordnance-Grade Steel
Magazine Type: Internal Box Magazine
Capacity: 5 Rounds
Detachable Magazine: No
Pattern: USMC M40A3 / D.D. Ross
This is an important distinction between the original M40A3 and later-service rifles that were converted to detachable-magazine configurations.
Scope Base
M40A3 30-MOA Scope Base
The M40A3 introduced a more modern one-piece optics mounting system.
PTG currently manufactures its M40A3/A5 scope base to the USMC print, with 30 MOA of elevation, an integral recoil lug and MIL-STD-1913 Picatinny dimensions.
Base: M40A3/A5 Pattern
Elevation: 30 MOA
Interface: MIL-STD-1913 Picatinny
Design: One Piece
Recoil Lug: Integral
Receiver Fit: M40A3-Spec Remington 700 Short Action
Historical Optics
Early M40A3
Early M40A3 rifles continued to use the fixed-power sniper optics associated with the preceding M40A1 era.
The combination of the traditional fixed-power optic with the much more modern McMillan A4 stock created the distinctive appearance of the early M40A3.
Later-Service M40A3
During the M40A3's service life, the Marine Corps began fitting rifles with a newer Scout Sniper Day Scope.
An official 2006 Marine Corps article specifically notes that the Corps was attaching the Scout Sniper Day Scope to its existing inventory of M40A3 rifles.
Later Marine Corps instructional material describes the M40-series rifle with a 3–12×50 optic, a five-round magazine and an effective range of approximately 1,000 meters.
Because optics evolved during the life of the M40A3, the historically appropriate optic depends upon the period being reproduced.
Bipod
Harris Swivel Bipod
The M40A3 was commonly fielded with a Harris-style swivel bipod attached to the front stud of the McMillan A4 stock.
Type: Swivel Bipod
Attachment: Front Sling Stud
Typical Height: Approximately 6"–9"
Configuration: Folding / Adjustable
General Specifications
Model: M40A3
Platform: M40 Rifle
Action: Remington Model 700 Short Action
Action Type: Bolt Action
Orientation: Right Hand
Caliber: .308 Winchester / 7.62×51mm NATO
Recoil Lug: .312" M40A3 Pattern
Barrel Manufacturer: Schneider
Barrel Material: Stainless Steel
Barrel Contour: #7 Schneider / M40 Heavy
Twist: 1:12" RH
Stock: McMillan A4 M40A3
Stock Material: Fiberglass
Stock Finish: Molded-In Olive Green
Cheekpiece: Gen 1 Adjustable Saddle
Length of Pull: Spacer Adjustable
LOP Range: Approximately 13"–14.5"
Bottom Metal: USMC M40A3 / D.D. Ross Pattern
Magazine: Internal Box
Capacity: 5 Rounds
Detachable Magazine: No
Scope Base: M40A3 30-MOA MIL-STD-1913
Muzzle Brake: None
Suppressor Mount: None
Historical Effective Range: Approximately 1,000 meters
Build Type: Made to Order
Estimated Lead Time: 6–8 Weeks
Original M40A3 vs. Later M40A3
Because the M40A3 remained in service for years, there is no single configuration that represents every rifle at every point in its service life.
For the historically minded collector, the major distinction is between the original M40A3 and later upgraded rifles.
Original M40A3 Configuration
Remington 700 Short Action
.312" recoil lug
Schneider heavy match barrel
McMillan A4 M40A3 stock
Gen 1 two-knob adjustable saddle cheekpiece
D.D. Ross-pattern hinged floorplate
Five-round internal magazine
30-MOA M40A3 scope base
No muzzle brake
No detachable magazine
Later-Service M40A3
Later rifles could incorporate revised McMillan A4 stock geometry, updated optics and detachable-magazine bottom-metal systems.
These changes helped transition the M40 platform toward the configuration that would eventually become the M40A5.
The B&B Firearms M40A3 is intended to represent the classic original M40A3 configuration rather than blending A3 and A5 features together.
From the M40A1 to the M40A3
The M40A3 retained the heart of the M40A1 while substantially modernizing the rifle around the shooter.
The M40A1 established the classic Marine Corps formula of a Remington bolt action, heavy match barrel and McMillan fiberglass stock.
The M40A3 took that formula further with an adjustable stock, improved sling attachment system, Schneider barrel, heavier recoil lug and modern Picatinny optics mounting system.
The result was a rifle that remained unmistakably part of the M40 rifle family while offering substantially improved ergonomics and adaptability.
Built to Order
Every B&B Firearms M40A3 is built to order.
Producing a historically faithful M40A3 requires specialized components and configuration details that are not found on a conventional commercial Remington 700.
The action, barrel, stock, bottom metal and supporting hardware are selected to reproduce the defining specifications of the original Marine Corps rifle.
Estimated Lead Time: 6–8 Weeks
Lead times are estimates and may vary based on component and optic availability.
Why the M40A3?
The M40A3 represents one of the most important transitions in the history of the Marine Corps sniper rifle.
It maintained the proven mechanical foundation of the original M40 while adding the ergonomics and mounting systems expected from a modern precision rifle.
Its Olive Green McMillan A4 stock, heavy Schneider barrel and unmistakable Remington 700 action made the M40A3 sniper rifle one of the defining precision rifles of the early 21st century.
For collectors, it represents an important chapter in Marine Corps history.
For shooters, it provides an opportunity to experience the configuration that bridged the classic M40A1 and the later M40A5.
For anyone assembling a collection of M40 rifles, the M40A3 is an essential part of that lineage.
Historical Reproduction Notice
The B&B Firearms M40A3 is a newly manufactured, historically faithful reproduction based upon the configuration and specifications of the United States Marine Corps M40A3 sniper rifle.
It is not represented as a U.S. Government-issued or surplus firearm and is not manufactured by, endorsed by or affiliated with the United States Marine Corps or Department of Defense.
