No, it's not. The numbers I quoted in post #10 are written into the criminal code and are absolute. You can legally cut any barrel to 457mm (17.99") and you can legally chop any long gun down to an OAL of 660mm (25.98") before creating a prohibited firearm. Since OP is using a manual action firearm he doesn't have to worry about the 470mm (18.50") barrel length limit to keep a semi-auto centerfire non-restricted.
Mark
ht tp://laws-lois.justice.gc.ca/eng/acts/c-46/page-42.html
There is the page for the law read through it make sure you understand it before cutting anything then do what you want. To get under the length it has to be made that way. Now the big question is if you got a shotgun that falls under that and was made that way and put a longer stock on it wouldn't that be illegal as well since it's under the length. The laws are kind of like landmines you got to watch were you step.
“prohibited firearm” means
(a) a handgun that
(i) has a barrel equal to or less than 105 mm in length, or
(ii) is designed or adapted to discharge a 25 or 32 calibre cartridge,
but does not include any such handgun that is prescribed, where the handgun is for use in international sporting competitions governed by the rules of the International Shooting Union,
(b) a firearm that is adapted from a rifle or shotgun, whether by sawing, cutting or any other alteration, and that, as so adapted,
(i) is less than 660 mm in length, or
(ii) is 660 mm or greater in length and has a barrel less than 457 mm in length,
(c) an automatic firearm, whether or not it has been altered to discharge only one projectile with one pressure of the trigger, or
(d) any firearm that is prescribed to be a prohibited firearm