Description
Browning M2HB .50 Cal Backplate Latch-Lock Pivot Pin, P/N 5013581, NSN 5315-00-501-3581
This Browning M2HB .50-caliber machine gun backplate latch-lock pivot pin, identified by part number 5013581 and NSN 5315-00-501-3581, is a small but important component of the M2's backplate latch system.
The pin serves as a pivot and retaining point within the backplate latch-lock mechanism. This allows the latch components to remain properly supported as the backplate is secured to or released from the rear of the receiver.
This listing is for one pin only. The packaging shown in the photographs is for identification and reference only and is not included with the item.
Historical Significance
The Browning M2 .50-caliber machine gun traces its design to John M. Browning's work on large-caliber machine guns after World War I. The improved M2 family was adopted during the early 1930s, and the heavy-barrel M2HB became one of the most recognizable American machine guns of the 20th century.
The M2HB served extensively during World War II, the Korean War, the Vietnam War, the Cold War, and later U.S. military operations. Its combination of range, durability, and heavy .50-caliber firepower made it useful from ground tripods, armored vehicles, trucks, antiaircraft mounts, cupolas, and many other installations.
The basic M2 design proved unusually long-lived. While mounts, sights, barrels, and supporting equipment changed over the decades, much of the weapon's core mechanical design remained recognizable across generations.
Small components such as P/N 5013581 were part of the support system that allowed the M2's major assemblies to be secured, removed, inspected, and maintained throughout its service life.
What This Item Is and Does
The M2 backplate assembly closes the rear of the receiver and carries important controls and components associated with operating the weapon.
A latch system secures the backplate in position. P/N 5013581 is the headed pivot pin associated with this latch-lock area. It provides a fixed support point for the moving latch mechanism while keeping the related component captured in the assembly.
Although it is a very small part compared with the receiver, barrel, or backplate, the correct pin is important when completing an original M2HB backplate assembly.
This listing is for the pin only, not the complete backplate, backplate latch, latch lock, grips, trigger, buffer components, or receiver.
Key Features
- Weapon: Browning M2HB .50-caliber machine gun
- Component: Backplate latch-lock pivot pin
- Part number: 5013581
- NSN: 5315-00-501-3581
- NIIN: 00-501-3581
- Assembly location: M2 backplate latch area
- Type: Headed pivot/retaining pin
- Purpose: Supports and retains the backplate latch-lock mechanism
- Quantity included: 1 pin
- Packaging included: No
- Packaging photographs: For reference and identification only
Why This Item Matters
Small pins and retainers are easy to lose when an M2 backplate has been disassembled or stored for decades. Missing hardware can also leave an otherwise complete backplate restoration unfinished.
The combination of P/N 5013581 and NSN 5315-00-501-3581 provides strong identification for matching this part to the correct M2 backplate assembly.
It is especially useful for collectors and restorers who want the correct military-pattern hardware rather than substituting a generic pin of similar appearance.
About This Item
The reference photographs show military packaging marked PIN and QTY. 10, along with the stock-number identification. The wrapper also carries a NOV 1962 marking.
The packaging is not included with this sale. The customer will receive one P/N 5013581 pin only, regardless of the quantity shown on the reference package.
This is military surplus and may show variations in finish, storage marks, light oxidation, grease, discoloration, or other signs of age. See the product photographs for representative condition.
Ideal For
- Browning M2HB restoration projects
- M2 backplate restorations
- .50-caliber machine-gun parts collections
- Military vehicle restorations using the M2HB
- WWII through modern U.S. military displays
- Armorer reference collections
- Technical and educational displays
Approx length 0.5", Approx width 0.25", Approx height 0.25", Approx weight 0.1 lbs.
Pictures are stock images of our inventory. Unless otherwise noted, you will not be receiving the exact item shown in the pictures. The pictures are representative of the item's general condition. The item you receive might be slightly better, or worse, condition than was shown in the pictures.
Please visit our page about order lead times here: 
