What is this 20mm?


This round has no markings of any kind anywhere that I can see.

The fuse is a sold brass dummy. The primer looks to be a tin or maybe cn material.

There is some sort of insert inside the case that looks a lot like a charge container you might see in a grenade. It is thin sheet metal, fits tightly inside, and has a small hole at the base that appears to be there to allow the primer to ignite the propellant. This round appears to have never been loaded.

Can any of you guys tell what it is?



Looks odd to me - that extractor groove is very small for use in an automatic weapon.


Thanks for your comment Tony.

Looking at the case with your comment in mind, it seems that the case wall is very thick. The insert that I mentioned above is actually one of what appears to be at least two concentric inserts. I can see the lip of a second insert that actually sits under the shoulder. Due to these inserts, the inside diameter of the case wall is actually such that it is uniform from the case mouth, all the way to the base of the case.



That sounds like a lathe turned item. Maybe no real case at all. Can you show us an image of the case head?