20x102 experimental projectile (China Lake “GPP”)

Does anyone know anything about this projectile?

I searched the web, and found a picture of a similar projectile on the BOCN forum
( Posted by EODGUY, answer #2 in this thread http://www.bocn.co.uk/vbforum/threads/73326-20x102mm-Examples)
where it was mentioned as experimental proof round from China Lake.

Odd on this projectile, is that the lower tail-part is thicker than normal (see pictures), so it doesn’t fit in a regular sized 20x102 casing…


Edit: Just uploaded new pictures (old ones photobucket are gone) in the hope someone recognizes this 20x102 projectile

Hi Geert,

This projectile configuration was designated “GP” or “GPP” (General Purpose Projectile) and developed at the Naval Weapons Center, China Lake, California. It was meant to be a multi-purpose load (armor piercing, fragmenting, fuzed) compatible with the M61A1 guns used by the three armed forces.

Here is a report from 1971 (requirement goes back to 1966): 1971 - NOLTR 71-95 - U. S. Navy 20-Millimeter General Purpose Projectile - 2.pdf (5.8 MB)



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Fede, thanks!
Why is the driving band pre-engraved?

As I understand from the report, this is a one-piece model for wind tunnel tests.

Thanks, given the detail of accuracy in this I wonder if they also had the projectile rotating during the test?

Yes Alex, the arrangement of having a rotating wind tunnel model is described in the report. For this reason, the model, shown in Fede’s photo, is much larger than 20 mm, about 2 inch. The report contains a drawing showing the outside dimensions of the real projectile.

Thanks Fede !

A six year old mystery solved ;-)

Jochem, indeed! The scale in the photo looked like 20mm and I did not even question it being an inch scale then!!!

And as we are on it, does a drawing of the actual projectile design exist? I mean all the internal details? I assume they must have done quite a bit testing of different arrangements.