7.62x51 Helicopter balance Test

I’ve just bought these 4 7.62 x 51 rds at auction, the headstamp is LC 66 and they come from a packet marked helicopter balance test, does that sound right ?

Those look like: “Dummy, Cartridge, Inert Loaded, M-172”

This is the standard gun functioning dummy used here in the US.

The case is filled with “Sodium Carbonate Monohydrate or equal” to replicate the weight of a loaded cartridge.

I can see these cartridges being used where the exact weight of a loaded ammo box or container (possibly containing many hundreds of rounds) for testing in a helicopter would be needed for safety reasons, but they were not made specificly for this purpose.

Quite common here in the US, but the label indicating a test use is interesting. Is this a handwritten label or more formal looking?


I haven’t got the rds from the seller yet so I don’t know what the label/packet is fully marked with.

It’s odd the friends we make…every walk of life

One of mine is a "master mechanic

Thanks for that.

This all reminds me much on the British 20x110 HS 404 “ballast dummies” which were made of one piece and had even no extractor grooves. They were linked and loaded aboard aircrafts to simulate flight characteristics of fully loaded / armed aircraft which are different from empty ones.

I have also seen British examples of these in the 30mm ADEN calibre.

I have a possible example in 7.62 x51 (emphasis on possible!). HS is (+) RG 80.

Dave S