25mm PGU-20/U API info?


#1

I have tried to locate some information on the 25mm PGU-20/U API cartridge, however there is shockingly little on the internet. Here’s what I have found:
– Navy used in past
– Marines use (used?) in GAU-12 gun in AV-8B Harrier
– 150g DU penetrator

I would like to learn more about this round so if anyone has links, pictures, diagrams, cutaways, etc., please add to this thread.

Also, I would like to find an inert cartridge (or fired shell) for my collection (please PM me if you prefer not to post that info) so any suggestions on that would be appreciated.

Thanks


#2

Projectile weight 215g, muzzle velocity 1,000 m/s. 150g DU penetrator in a steel body with a thin steel windshield.

As far as I’m aware it has only ever been used in the AV-8B Harrier.

It was made by GD-OTS but they no longer advertise it on their site. Presumably it’s no longer in production.

If you ever manage to find two, reserve one for me :-)


#3

The AC-130U gunship had a 25mm Gatling gun and this would have been one of the loads it could have used (the gunship ammo is varied depending on the likely target set). These guns have been removed, or are being removed and replaced with the GAU-8 because the 25mm ammo is expensive and we have huge quantities of GAU-8 30mm ammo left over from the old warplan requirements for a war with the Soviet Union. This excess 30mm would just be scrapped so it is essentially free to the Gunships, and frankly is better suited for the mission. Some (like me) consider it a stupid decision decision to put the 25mm in the AC-130U, but it wasn’t the only stupid logistics decision when the aircraft was put into development. Will tell that story over a beer sometime.

The Air Force version of the F-35 is scheduled to have a 25mm Gatling but no idea what ammo it would carry. Unlikely it will get low to try to kill armor with that little gun so it will likely carry air-to-air loads.


#4

Hi Lew,

Actually it wasn’t the GAU-8/A that was due to be fitted in the AC-130s, it was the single-barrel MK44 Chain Gun firing the same 30x173 ammo. The last I heard they had dropped the idea because of unspecified accuracy problems, which rather surprised me.

The 25mm GAU-12/U was adopted as a replacement for the 20mm M61A1, so it was a more effective weapon at the time.

The F-35A will be fitted with an internal 25mm GAU-22/A, which is basically a four-barrel version of the GAU-12/U. The STOVL F-35B and USN F-35C will be able to carry the same gun in an under-fuselage pod. See these two pdf presentations:

dtic.mil/ndia/2008gun_missil … rDavid.pdf

dtic.mil/ndia/2008gun_missil … ouglas.pdf


#5

Tony,

Super presentations. Thank you very much for posting them. Impressive machines to say the least! And who said engineering had to be boring?

Dave


#6

I concur with DaveE. Great stuff there. Now, just gotta get my hands on one of those rounds. Oldest son works for Lockheed. Hmmmmmmm.

POSTED WITHOUT PROBLEMS**


#7

Small typo there, Rick - you need two of those rounds!


#8

Roger that.


#9

Tony, Thanks for the info. My data was a few years old and I was told they intended to use excess GAU-8s. I guess it got more complicated than it sounded. It is possible the GAU-8 stresses could be enought to require a major structural upgrade to the aircraft in that area, or other technical considerations could have made it impractical.

Pod guns don’t have a good track record air-to-air from what I have seen and I can’t imagine the F-35 will use a 25mm gun air-to-ground. It will be interesting to see how the pod guns for the F-35 work out.

Cheers,

Lew


#10

Very true, the vibration of firing tends to shake them out of alignment with the sights. However, I get the impression that the F-35 pod is rather more rigidly mounted than the usual quick-detachable ordnance mounting used by most gunpods.