Marlin used what they called “micro-groove” rifling, they are supremely accurate.
I like to collect the ones made between 1980-1985.
Full length 22” barrel and 18 round magazine.
Later they shortened the magazine to 14 rounds and the barrel to 19”.
To get the year of manufacture simply subtract the first two numbers of the serial number from 100.
ie, serial number starts with 19******* was manufactured in 1981.
From 1973 to around 2000 all Marlins used the same serial number system.
I used to have 2 Marlins once upon a time (when I was a kid)
The kind of rifling is relevent only WRT the type of bullet used. Micro is good with cased bullets chiefly.