Korean war Mk IV heat stamp?

[Apache-8]

Hello there. I recently picked up a Korean era Mk IV shell that got retrofitted as a Mk V some point latter in life, and have been having trouble identifying the manufacture. the heat stamp reads: 

 

ROC              4

            JJ

MA              1952

 

at first I thought it was just and RO&CO that stamped wrong but after doing some digging I found a few other helmets with the same heat stamp except for the characters where the JJ is. I haven't been able to find anything about a manufacture with the stamp ROC so would this be an RO&CO batch that was stamped badly or would this be some other company, from another commonwealth nation perhaps? any help is greatly appreciated.

- Apache-8