The "C-broadarrow" as a Canadian military property mark was introduced by Militia General Order 213 of 1907 .....
As you may know, while the broadarrow (and its various Colonial/Commonwealth variants) was a government acceptance and property mark used primarily (but not exclusively) on military
matériel, "opposing broadarrows" - i.e. two such arrows oriented point to point (either slightly separated or points touching) was a
disposal mark - i.e. signifying that the firearm (or other piece of kit) had been "sold out of service" - i/e/ disposed of by the Crown and thus no longer government property ....
If a Snider (or Martini) bears anything like the C-broadarrow, it is more likely to be an opposing broadarrows
disposal mark applied in 1907 or later ....
One of my Canadian-issue Snider-Enfield Mark III Short Rifles has such a disposal mark which is quite impressive -