RE: What makes the 7400 SO in accurate?
I never knew they were so inaccurate. Where did you see that? I have one in a 270win. I had POI changes. It would shoot an honest 1.5MOA but my complain was POI changes. I finally figured out what it was. The new forearm I put on it was a tad too long. Which forced the pressure up on the barrel when the screw was tightened. I took a shim and put on the end of the gas tube to make sure the forearm wasn't touching the action. Then all was good. I never have, but plan on taking a dremel to it and taking off some of the forarm instead of the shim.
I bet I have over 500 rounds thru the gun. I have had it since 1988 relatively trouble free. Can't complain. Only issue was building a load for it. I had to pick my powder to make it cycle correctly. But also had to do the same for a Browning semi. I tried all the 4064 and vargets (fast burners Sierra recommends), and wouldn't cycle good, so tried 54gr of IMR4350 with 130gr gameking and shoots and cycles great.