Anthony,
This dot thing has grown like a rumor the school marm and the preacher are carrying on.
This is for all folks-----AIN"T NO DOTS ON 300 TANGS, especially any that count toward dates.
Your 311 is the last model made. There are only a couple of variations in the whole model line.
There is a Buck, Made in U.S.A. with 311 stamped on reverse. - this is the oldest
There is yours Buck,311, U.S.A. then within this era there is spell they put little nylon pillows in the blade well so the blade edges would not hit bottom, but they only did this a short while. I think it was because they had a run of blades that were stamped wrong and when folded not enough tang 'foot' existed to keep it from hitting bottom. Or the pivot hole could have been drilled wrong.
Then there was a short run of serrated secondary blades and very very rare yellow scales, all of whch still fall in the Buck, 311, U.S.A. time period. There is also one made for Winchester with 'Winchester' stamped on escutcheion plate in place of the knife,bolt and hammer.
The MiUSA 311 1972 -74 , the rest from 74 to 90. Serrated 88-90.
FYI Next newletter will have a history article with photos on the 311. Heres photo to tide you over.
300Bucks
These are the only two tang stamps you will see, every other difference will be somewhere else on knife.