Complete your U.S. aircraft cannon restoration with this specialized component that serious collectors and restorers know is often the hardest piece to track down. This 20mm M39 Ring Seal is an original part for the M39-series 20mm revolver cannon, identified by Part Number 842-1725 and NSN 1005-00-674-7803.

The M39 was one of the most important American aircraft cannons of the Cold War era. Developed in the late 1940s and standardized in the 1950s, the M39 family became a well-known 20mm weapon system used in aircraft such as the F-86, F-100, F-101, B-57, and later the F-5. Its compact revolver-cannon layout gave U.S. fighters a hard-hitting internal cannon at a time when aircraft armament was rapidly shifting from machine guns to more powerful automatic cannon systems.

On a weapon like the M39, the small internal parts matter just as much as the big visible assemblies. A component like the ring seal may not draw attention at first glance, but it belongs to the family of precision-fit parts that help preserve the mechanical integrity of the cannon. In restoration terms, this is exactly the sort of detail part that separates a visually complete project from one that is truly correct.

Because the M39 is a gas-operated revolver cannon with tight tolerances and carefully fitted internal components, sealing parts are an important part of the system’s overall design. That makes an original M39 ring seal a desirable item for:

M39, M39A1, M39A2, and related M39-series cannon restorations
Cold War aircraft armament collections
Museum displays focused on U.S. aircraft gun systems
Technical reference collections of original U.S. ordnance parts
Spare parts inventories for advanced restoration work

What makes parts like this so collectible is that they were rarely saved once separated from the gun. Large assemblies tend to survive. Small internal hardware, seals, plungers, springs, and retainers usually disappear first. That is why correctly identified original M39 components remain so desirable today.

This item is especially useful for anyone building out a historically accurate M39 parts set, studying the internal makeup of the cannon, or preserving original U.S. aircraft armament hardware for future projects. It is also a strong collectible in its own right for those who focus on rare Cold War aircraft gun parts rather than only complete weapons.

Whether you are restoring an original 20mm M39 cannon, building a reference display of authentic U.S. aircraft armament components, or setting aside rare spares while they are still available, this M39 Ring Seal is exactly the kind of correct, properly identified detail part worth having on hand.

Ideal For

This part is an excellent fit for:

20mm M39-series cannon restorations
U.S. aircraft armament collections
Museum and educational displays
Technical parts-reference collections
Spare-parts inventories for original Cold War cannon systems

Approx length 1", Approx width 1", Approx height .1", Approx weight .1lbs.

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.

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