since the Chinese op rod springs are slightly smaller in inside diameter than US GI and most of the US made commercial op rod springs, an op rod spring guide for use on a Canadian [ METRIC SPEC ] M14 clone, MAY BIND ON THE LARGER DIAMETER O.D. OF THE GUIDE.
So if you get a US spec guide, figure on a US spec replacement spring as well.
The Canadian made guide rods are consistently a bit smaller in O.D, and will work with BOTH the GI spec springs and the original smaller I.D. METRIC Chinese op rod springs. However, the smaller Cabnadian/Metric guide rods will show a tiny bit of play [ ripples ] if used with the larger springs. So for ultimate happiness, like many things in life, HAPPINESS here as well can be defined as A TIGHT FIT ... but NOT TOO TIGHT!