wondering if the barrel length rules also apply to revolvers ?
It
especially applies to revolvers, as the major reason that ~4-1/8" was chosen to be the cut-off point was that 4" is a very standard barrel length for revolvers (including many police side-arms which may otherwise have been surplussed). Thus the authors of the Law were able to Prohibit a large swath of hand-guns rather easily.
Smith & Wesson's specification of four inches for your revolver is a
nominal measurement; the actual barrel length *may* differ enough, in the right direction, to qualify the gun in question as no longer the most deadly, concealable, evil, scary thing that ever tried to cross the border. (Conversely, you may be boned even worse than you knew.)
The barrel length of a revolver is measured differently from other fire-arms, in which you would close the bolt or breech and measure back to the face. From the
Criminal Code Part III
Section 84(2), the length of a barrel of a firearm is:
(a) in the case of a revolver, the distance from the muzzle of the barrel to the breach end immediately in front of the cylinder.
Which makes the simplest way to measure just turning the cylinder mid-way between chambers, putting a stick down the barrel until it stops at the cylinder face, marking the stick across the crown, and measuring that depth.
The 686 SSR does not have a muzzle device, integrated or removable. If it did, that could complicate the measurement, as you do not include such in the length.
By S.84(1), a hand-gun with a barrel
equal to or less than 105mm would be Prohibited. This means a mere hair's breadth over 105mm is not Prohib. (if you can prove such a correct measurement). You're looking for about 3,5mm over the nominal length, and it could very well be there.
Once you've checked the measurement yourself, you will know whether it will be worth attempting to have the gun officially Verified as Canada-legal, whether it's border-line where you take your chances, or whether there's just no way it will ever pass. Note that even if you have a gun that's a clear winner (let's say definitely over 106mm), it's possible that they will make it difficult to Import and Register it, saying things like ‘The FRT shows this model came with a 102mm barrel.’ Don't hand them any piece of paper that says your gun has a 4" barrel (thankfully it hasn't been Registered in Canada already), just tell them it's a 106mm barrel, and why yes, they can measure it any time.
Obviously, arrange everything ahead of time, with calls and correspondence to the Canada Border Services Agency and the Canadian Firearms Centre; don't just show up with the gun at the border.