R U sure that the top of the front sight is being held well down into the rear sight notch @ firing ?
I've never ran across a Marlin that didn't shoot fairly close to the barrel sights - usually not needing a taller front sight until a receiver peep was added.
A previous owner
might have changed the front sight, for a lower one than issue, but the correct font sight height can be calulated after the amount of inches high @ 100yds the rifle is hitting is plugged into the formula.
www.skinnersights.com has a sight height calculator on his website, along with front sights.
Williams Gun Sight Co, Lyman Gun Sight Co, and Marbles Outdoors are only three of the several other companies that make sight blades of various heights, thickness', and sight materials like Ivory or gold or fiber-optic beads.
IIRC, your rifle's front sight is a direct barrel mount (no ramp) - so IF you obtain another sight of whatever height or bead, be sure to get one with a WIDE base that completely fills the barrel dovetail (side-to-side).
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