What Op rod spring guide should I choose?

[can14]

I go with the basic idea...the spring is round and the NM op rod guide is also round. The spring will compress with out to many issues because it is supported 360 degrees.. The GI rod is fine, but the spring slides on two points, the top and bottom of the guide. So you do have some improvement.

 

[Travis Bickle]

It's all about mechanics and the resulting harmonics created in your rifle.
Now, in order to realize the potential effect of the guide rod in any given rifle, the oprod guide on barrel should correctly positioned and anchored to eliminate movement on the barrel.
At this point, the NM guide rods "should" cause a more consistant cycling path for the oprod. Putting it simply, the stock rod allows the spring to compress unevenly and as this wavey, uneven compression takes place, the spring has an effect on the oprod. This effect leads to inconsistant return to battery, which in turn gives inconsistant harmonic vibrations through the barrel.
Am I losing anyone here?
So, as found time and time again by a great many M14 shooters/builders, the addition of an NM guide rod is beneficial to producing repeatable and more consistant accuracy/groups.

These guide rods and their ability to force the spring to compress evenly have a secondary effect which is also beneficial to your rifle. The fact that the action cycling is more consistant in the "patths" the parts move , this leads to less wear of the oprod and receiver at their friction points/bearing locations. Ie: bolt roller and pocket, oprod tab and receiver track ect.

Overall, while replacing sights and flash hider assemlies is an many cases a must do upgrade on the chinese rifles, I also feel that anchoring or NM conditioning the oprod guide and adding an NM oprod spring guide rod are the first steps to seeing the baseline accuracy potential in all M14 type rifles.
Remember, it's just my opinion, and I don't sell/market/manufacture or represent any of the currently availlable NM guide rods that are out there.

I get what you're saying in a certain way.

Has this ever been tested practically?

What type of improvements are we talking here? Shrinking a 2 inch group at 100 meters to a 1.989" group? Or is it going to make a 6" group into 1" group?

I just tac welded my Norc Op Rod guide in place to the barrel lol and I can get a 1.5" group at 100 meters with irons if I use very good ammo and take my time with a good visible target. Good enough for me in every way.