Very small inconsistencies can mean that timing is off, and feeding issues can occur.
In addition, a proper wood-to-metal fit is a critical indicator of quality in a lever rifle.
Microgroove rifling is described in the patent as having 5 grooves for every 1/10 of an inch bore diameter, and that the driving side of each land would be "tangentially disposed" to prevent accumulating fouling in use.
A brother of a friend of mine has the Marlin 6899 chambered for Mag. I have not had a chance to shoot a deer with mine since rifle season was over when i got it, but i have seen my dad kill 7 deer with his and the hornady has done the job.
* Not all records are the same as far as content described above. AGI is not responsible for errors or omissions in the records. The second letter of the date code is as follows: F = 1962G = 1963H = 1964I = 1965J = 1966K = 1967L = 1968So a date code of "JK" would indicate that rifle was made in October of 1967. Straight stock, 21 ½ inch barrel, 40 ½ inch over-all. If you give us that letter we'll be able to tell you the year it was made. Perhaps there is some obscure marking that is near impossible to find – like markings on Waterford crystal, but I see nothing else. No other identification can be found other than the Marlin insignia Doesn't seem to fit into the date codes above. There will be a letter before the serial number that will probably be between "M" and "S"" in the alphabet.for what was named Micro Groove Rifling, which was a departure from the standard "Ballard," or cut rifling.One purpose of Microgroove rifling was to increase the speed of producing rifle barrels.