I recently put a Skinner Peep on my 336. I had to replace the front sight with a taller one, (.183" of an inch taller). The best thing to do is mount the skinner peep with it cranked down as low as you can get it, and go to the range, and shoot a group. Then use his formula to figure what you need to do as far as front sights go. You may get lucky, and your factory front will work. Good luck!!
Front Sight Height Calculator
When you are unable to adjust the rear sight to work for your rifle because the rifle shoots high you will need a taller front sight. To eliminate the guesswork, you can calculate the additional height needed using the procedure below.
1. Shoot your rifle at a known range (say 50 yards). Note the distance you need the impact to change (say 6 inches lower).
2. Measure the sight radius of your rifle (22 inches on most Marlins).
3. The change needed is calculated by changing all measurements to inches then multiply the sight radius by the desired change in impact and divide that product by the range in inches.
4. The result is the additional height needed for the front sight. To get the height of the new front sight add the current height and the calculated number from (3).
Example:
I need to shoot 6 inches lower at 50 yards with my 1894, 44 Mag. With a 22 inch sight radius. My current front sight is .350” tall from the bottom of the dovetail to the top of the sight.
50 yards = 50X36=1800 inches
Desired height change is = 22 (sight radius)X6 (desired change)/1800(range)=.073 inches. My new front sight needs to be .350+.073 or .423 inches tall.