Yes the larger size OD of any brand NM Op rod spring guide will tighten up the tolerances between the op rod spring and the ID of op rod. The USGI op rod guide allows the spring to bunch around it with out interfering the ID of the op rod. This is probably more true if you use an aftermarket spring such as the extra power Tubbs. The solution is to polish, notice I didn't say grind, the ID of the op rod as suggested above. It wouldn't hurt either if you inspected the NM op rod guide for any bright spots that the spring is rubbing against. I've polished these "high" spots down with 400 grit sandpaper and reblued. During any take down, I look look to see if the blueing is worn off. If so I'll sand/polish a little more off, and reblue. I had a 1991 Bush rifle that made more noise than my neighbors dog, when pulling back on the op rod handle. Doing the above cured it. It's just a matter of getting these mating parts to work smoothly together. dozier