Peter is right about the Canadian property mark.....A broadarrow in a C. The broadarrow (
British
) dates back to somewhere in the 1300s and denotes King's stores.
Canada
started using a Canadianized form in the late 1800s by putting a C around the broadarrow, thus denoting Canadian government property. After WW2, the RCMP complained that there was so much surplus on the market with the C/l\ that they could not tell what was sold and what was stolen. By 1949 the C/l\ was officially dropped, although you will still find it stamped on kit much later (likely due to manufacturers following DND manufacturer drawings). As well, armourers seemed to continue to electro-pencil it onto small arms parts.
Post 1949, there is a styalized arrow that inspection services used, but it was more of an inspection mark than a property mark.
There was also the C in an oval on some
Enfield Rifles
that were thought to be used by shooting clubs or at Connought. It is thought the C in the oval denoted "competition", and usually would also have a 5G or a 6G on the wrist, likely denoting 5 groove or 6 groove rifling.
As to your C in a circle, I have seen a lot of Canadian weapons, and have never seen that mark on one.
Canada did end up with a bunch of no4mk2 rifles as part of the Ranger program. LB rifles were becoming short in supply, so the Canadian government went onto the world market to purchase more Enfields, and ended up with no4mk2 rifles around the 1999 timeline. No specific support was ever listed for the variations of that type rifle. All the no4 Enfields are now being pulled from Cdn military service as we speak. Any parts that are not common to the Cno7 rifle have been listed as being for disposal.