This 20mm M39 Operating Slide Rammer (Left Hand) is an authentic U.S. military surplus part designed for the M39 revolver cannon, the well-known 20mm aircraft autocannon developed during the early Cold War for high-performance American jet fighters. Identified by Part Number 8400336, this left-hand rammer assembly is a critical component of the cannon’s internal operating system and forms part of the left-hand operating slide assembly. In service, parts in this section of the gun were responsible for helping control the feeding and chambering cycle during high-speed firing operations.

The M39 cannon was one of the first successful American revolver-cannon designs and became standard armament on aircraft such as the F-86 Sabre, F-100 Super Sabre, F-101 Voodoo, B-57 Canberra, and later the F-5 Freedom Fighter / Tiger II. Chambered in 20×102mm, the M39 family gave U.S. aircraft a compact, hard-hitting cannon system capable of a high rate of fire, making it one of the defining aircraft guns of the 1950s and 1960s. The operating slide rammer played an important role in that performance by supporting the gun’s feeding and chambering sequence under rapid-fire conditions.

This specific example is the left-hand version, which matters to serious restorers and collectors. The M39 family was produced in both left-hand and right-hand configurations depending on the aircraft installation, so correct handed parts are essential for historically accurate restoration work. This is not a generic internal part or shop-made replacement. It is a proper M39-series component intended for the left-hand operating slide assembly, making it especially valuable for anyone trying to complete or document a correct left-hand setup.

Product Specifications:
Condition: Surplus original part
Orientation: Left Hand
Part Number: 8400336
Compatibility: 20mm M39-series revolver cannon
Application: Left-hand operating slide assembly / feeding and chambering system component

Historical Significance:
The M39 cannon marked a major step forward in American aircraft armament. By adopting the revolver-cannon concept, the U.S. military gained a lighter, more compact 20mm weapon capable of delivering much greater firepower than earlier machine-gun armament. Specialized internal parts like the Operating Slide Rammer were essential to that performance. Today, surviving original M39 internals are increasingly difficult to find, especially handed components like this one. That makes this part a strong addition for collectors, restorers, and historians focused on Cold War aviation ordnance.

Ideal For:
Restoration projects involving M39-series revolver cannons
Aviation museums and static display restoration
Spare-parts inventories for Cold War-era aircraft armament systems
Collectors of U.S. military aviation ordnance
Technical reference collections and educational displays

Approx length 5", Approx width 5", Approx height 1", Approx weight 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: Order Lead Times