20mm Link Question

[US-Subs]

I was sent a question on some 20mm links that a museum curator is trying to identify - not my thing, so I told him that I would pass it on to the forum and see if anyone here can help. The information given is as follows:

"Attached are photos of some 20mm ammo links we received
from the Armament Museum at Eglin. I can look them up by the part numbers
11698241 and even know the national stock number (1005-780-8054) but nowhere
can I find data on what model they are or what type of gun system they were
used for. Everything just reads, Conveyor Element."

Any help would be appreciated. Here are the two photos provided.

 

[weberoed]

They look like the same links we used when I worked at Primex (now GD-OTS). We were loading PGU 32 (I think) 20mm SAPHEI rounds, the same links were used on the M55, 56, etc. They were made by a small firm that was in CA, but ATK bought the company and they are now making them at Lake City