I'm not 100% sure on the assembly date since other factors could be involved. Personally, I don't research a rifle's age using barrel codes. I look up action serial numbers documented in the Lacy book and get a very close date down to the month and year. Also, various features of the action help confirm the age and when it was likely made (trigger, bolt shroud, bolt handle, action D&T for a Williams side mounted rear sight, action cutout for stripper clips, etc...) . Taking your newly acquired rifle as an example, follow my reasoning.
The original rifle was likely chambered in .222 and left the factory around Nov. 1967. Owner could have shot out the barrel from high volume shooting at prairie dogs. Due to poor accuracy issues, rifle is pawned or sold to a new owner. Years later, another owner replaces the barrel with a $25 take-off found on a table at a gun show. Replacement barrel has stamped codes dating it for a completely different year or decade. When I buy used 700's, I want to know how old the action is, not the barrel.
Here is an actual example of a rifle I bought several years ago from a pawn shop in North LA. It was listed as a custom Rem 700 in 25-06. Based on the components, I could tell it was a "Frankenstein" rifle, that was assembled from various components over multiple decades. The action SN is 1754, dating it back to 1962, one of the first rifles (actions) made by Remington. My guess it was originally chambered in 30-06 or 270. Barrel was a factory 25-06 chambered take-off, with all the normal stampings that was dated to 1998. Stock was an HS Precision from the early 2000's. BA and the stock were all painted with fresh cerakote to appear as a new custom build. I ended up parting it out and selling everything. Hope that helps
