What's This
 

I have this breech block from a 105mm, not sure on the model, if any one can shed some light on this, it is spare to my needs, Cheers.

What are the numbers on it?

105mm Breech Block
 

The numbers are : 30541 on the face and D7238455 and H.T. 0B403 on the bottom, make sense?, cheers.

Are you sure it's a 105? My money would be on 76mm from M41 tank.

Just checked my manuals, almost certainly M32 76mm gun from the M41 tank.

Sounds like that is the answer we are looking for, and it sort of makes sense as we did have a few M41's over here. I bought it 20 years ago at auction, described as 76mm Scorpion breech block , but at the time having never seen a Scorpion one ,it just sat on the shelf with that label on it, well done!.