I would not rule this out as one of the Spencer carbines acquired by Canada. The serial number is in the range (albeit a very great range). The cut-off is supposedly not on Canadian guns but I have yet to see a definitive "rule" that states Canada only acquired those without a cut-off.
The inspector marks were found on the Starr carbines acquired by the UK. I have seen pictures of at least one other carbine that is quite likely a Canadian issue. It does not have the cut-off but does have the US inspector marks.
The inspector marks were found on the Starr carbines acquired by the UK. I have seen pictures of at least one other carbine that is quite likely a Canadian issue. It does not have the cut-off but does have the US inspector marks.