The Norc Op Rod Guide is basically interchangeable with the US GI ORG, however the NORC ORG may vary a bit in dimensions and hardness due to the Chinese not holding specs as closely as GI.
The biggest problem here is that the NORC ORG ROLL PIN is brittle and breaks, so a proper fitting, properly hardened ORG pin is probably more critical than the guide itself. I use red loctite, and a peening center punch to rough up the barrel under the ORG, paying special attention to tightening up the pin channel. Then I set the ORG in place by aligning the tip of the op rod with the gas piston rear end [ Mr big fat rubber mallet is your friend ]. Of course, before doing this job, you want to make sure the barrel [ and the gas asasembly ] is properly indexed FIRST!!!! Otherwise you are just compounding the indexing/misalignment problem.
This ORG alignment is critical to proper op rod travel, so that the op rod tab does not wear too much, or jump out of the op rod track in the receiver.
Let the red loctite set up overnight before shooting, and this is about as good as it gets for this section of the M14, if you stick with an OEM design ORG
The rectangular OP ROD Guides included with an AKM stock, are IMHO a vast improvement over the OEM GI and NORC op rod guides, as they allow the barrel to be "free floated" with the two tensioning screws that fit into the sides of this part. A bit of clearancing in a wood or fibeglass stock forend, a bit of bedding, and VOILA ... you get a much better design than original.
Just my thoughts on the subject ....
[;{)
LAZ 1