Model 700 Date / Info

[IDPA_Tom]

I recently received a Model 700 in 7mm Rem Mag from my Father-In-Law, and am trying to date it. All the dating schemes I've seen point out a two character date code on the barrel. This rifle has a four character code on the left side of the barrel: "D A", followed by an "N G" which are not quite in line with the "D A". I'm wondering if some previous owner had some fun with this rifle or something and added the "N G". Or maybe the "D" is the inspector mark, "A" is month (March), "N" is year (1966), and "G" is the "assembly"? Serial number is 1853##.
Based on conversations with my Father-In-Law, I think it was manufactured in the late 60's.
Is anyone able to help? Thanks!

[600RemGuy]

Would tend to believe the March, 1966 build date. While the receiver serial number should really be far closer to 190xxx, it is not uncommon to have a receiver a few months older than the build date as serial numbers are added when the receiver is built, not when the rifle is built.