The most accurate ML rifles I have are old original rifles. The most accurate is seven groove equal land groove widths.
Bore is .366, groove is .377, gain twist ending at about 36 inches. The bore has a slight taper all the way to the breech.
From the bench I have shot several one inch five shot groups at one hundred yards with the rifle. The rifle has the Nock system breech and weighs only ten pounds.
Joe.