There's an old post here that discusses it pretty thoroughly. I called Remington and got different answers on different days and from different people. One of them was an older one with a Hart Barrel and a Muzzle that was flat but crowned. I can tell you from experience that figuring out the DOM of a 40X is an exercise in futility. I am an old man now two tours Vietnam 68-69. My shooting buddy has a 308 LTR Remington in the 308 that shoots cloverleafs at 100 yards. Too cold and windy today for me to shoot this one, but can't wait. It shoots in my hands and a shooting buddy's hand a true. I bought a used HS precision stock for it. I recently bought a Dick's Hardware special in a 308 for 449. Be assured I don't know squat about Remington rifles other than I sure like to shoot them as of late and am impressed with their accuracy. Not sure Remington put these on other production guns. Other info I have found says it is tough to figure out the manufacture dates on these 40X's from serial numbers. According to this article my gun (figuring 500 guns per year and based on the serial number of his 66 gun) my gun would have been made in the mid 80's. If I use those barrel codes the gun was made in 1965. I should have looked more closely at the link you supplied and did not recognize it as a barrel code. Whirlwind Thanks for willingness to help.
