20x102 APFSDS 'flechette' round - info needed

Added this beauty to my collection today.

I can’t find any info on it, just that it was an experimental 20x102 round made by Lake City Ammunition in 1968. (as marked on the original casing)

So please, any info regarding this round is welcome.

Take a look at Historical Development Summary of Automatic Cannon Calibre Ammunition 20-30 millimetre available on line here:


See the section on flechette rounds, page 113; or the section on penetrators page 44 and so on. Hope this is of some use.


Thanks Brian.

That’s the general info on a flechette round, but i’m looking for specific info on this type of fiberglass sabot.

Orpeus, just wanted to say that I spent some time on your site and it was great! Your 20MM collection is off the charts.


This is puller sabot flechette made by AAI Corp. c. 1972. It was tested in a standard M61A1 gun fitted with a sabot diverter.

Thanks Fede.
I looked at those patents and found a brief description of the round here:

patent US 4656919 A : lightweight steel penetrators sabotted with unidirectional fiberglass, glass-filled polyester, molded Rynite 545™, and carbon-filled 6/6 nylon

It seems almost correct for the round i have (except my penetrator is probably not a steel one, as it is only low magnetic), so now i’m really looking for a drawing/patent of these projectiles/rounds itself…

That patent is actually a later application (1985) related to the 30 mm GAU-8/A cannon, and the patent covering this 20 mm puller sabot projectile is no. 3834314 of 1972. This drawings shows a round with the annular seal inside the case.

Thanks Fede!