The Krinker Plinker is a different situation. Rimfires are not restricted because of their barrel length but rather by overall length. Over 26" = non-restricted, under 26" = restricted. No matter how you alter the length (longer stock, welded on flash hider, etc.) as long as its minimum length (eg. when the stock is folded) is a permanent 26" or more it is non-restricted. Welding on a flash hider to get it to 26" or more is a perfectly acceptable method of doing that.
Reaper is bang on the Barrel mod the way it was explained to me is that adding anything on to the barrel is not a mod that in the law is acceptable ,Regardless if you are trying to change status from restricted or simply trying to lengthen the barrel to utilize another stock it is a illegal modifaction ,if in doubt contact the RCMP Firearms Lab they will let you know.