As I indicated previously, I am not a Canadianicon nor a Ross expert. The Numbers, other that he serial number, means nothing to me. I had a MKII 5* that was not marked LC but it did have the enlarged chamber. I know because I fired it. I am surprised that a "US" charged ROSS did not have the "LC" markings. I shall conjecture that the MKII 4* that reverted to the MKII 3* may not have the large chamber. A Canadian military collector may be able to provide additional info.