This is an issue that has nothing to do with barrel length and everything to do with how the RCMP classify firearms. The RCMP have for a long time considered most modern AR-10s upscaled AR-15s due to the heavy influence of the AR15 on the KAC SR25 (AR10+AR15=SR25?) therefore restricted as a variant however the original AR-10 is in fact non-restricted as it is not named in the legislation specifically and also very importantly predates the AR-15 design so therefore cannot be a variant of.
North Eastern Arms (now BCL) was the first manufacturer to test the waters against the RCMP and see if they could get a non-restricted classification for their moden manufactured AR-10 known as the 102 which the name in itself pays homage to the original AR 10-2 which is non-restricted. Now Stag has done the same thing with the Stag 10 and there's also now a pre-order for a Troy 102 as well not to mention rumors of a non-restricted AR-10 from a manufacturer called radical firearms.
Rule of thumb is with AR10's is that 99% that you will encounter manufacturer wise will be restricted irregardless of barrel length as they have not had someone take the time to make a case for their freedom
