I have two 336 marlins and one NEF in 30 30. All are Micro Groove barrels. The oldest from the late 70's shoots well with oven treated wheelweight s and gas checks, and misses the backstop with paper patched Lee 150 grainer that has had the gas check shank removed the NEF shoots them almost as good as itwill oven treated with gas checks. the 336 made in 1982 will shoot almost a cloverleaf from 75 yards with both loads.

It is worth a try. The paper patched loads are pure lead and all loads are 36 grains of H 4350.
Ihave not done a chamber cast to examine throat or the lead to the rifling.
The plain based bullets shoot great in all 3 rifles with 1400 to 1500 fps loads of unique or 2400.