1. Measure the diameter of the barrel at the point of the rear sight is going to be installed and at the point of the front sight going to be installed (example: 1.0" rear sight and .750" front sight).
2. Divide the diameters by 2 (example: 1.0” / 2 = .500” and .750" / 2 = .375").
3. Check the rear sight height adjustment chart. You want to be about 1/3 up from bottom adjustment. using a sporting rear #67 adjusts from .300" to .510". Total adjustments is .210". Divide .210" / 3 = .070". Add the .070" to the lowest adjustment height (which is .300") and you come up with .370". This is 1/3 up from bottom adjustment.
4. Add the 1/3 adjustment to the center line distance (example: .370" + .500" = .870").
5. Subtract the front sight center line figure from the rear sight height (example: .370" + .500" = .870").
6. You need a combination of front ramp and front sight with the height of .495”. Ramps are measured from the base to the bottom of the dovetails. Front sights are measured from the bottom of the dovetail to the top of the bead.
7. Or you could go with a front sight height of .588". .495" (height need from top of barrel to top of sight) + .093" (which is the depth of the dovetail cut in barrel).
Marble Arms® Front Sight Chart/ Fiber Optic 3/32" Bead
Marble Arms® Front Sight Chart
The Marble Arms® front sight, with its unique contour, has set the standard since 1900. These magnificent front sights are the number one choice of precision shooters and serious hunters.
Marble Arms® Contour Front Sights are strong, stable, and give your rifle a true traditional look. Marble Arms® Contour Front Sights are available in two widths for ramps or barrels along with various heights from .260 inches to .570 inches. Choose a gold, ivory or fiber optic bead. (Orange or Green)
Marble Arms® has developed a line of uni-ramp front sights that fit all rifles, shotguns, and muzzle loaders that use screw held front sights. Some guns will have to have a new mount hole drilled and tapped. The brilliantly glowing fiber optic cables are installed and permanently flared to the sight. Both ends of the optic cable are carefully polished to enhance light transmission and are uniquely protected from UV damage due to long term exposure to sunlight. Each one is precision CNC machined from solid steel to our exact standards. These fine sights are machined, polished, and blued to match your gun.
The Marble Arms® Uni-Ramp Front Sight is available in fluorescent orange and green in a variety of heights.
Marble Arms® Front Sight Ramp with Dovetail Slot
Calculating Rear & Front Sight Height Combination
These fiber optic front sights replace the standard factory sights for the Ruger® Super Redhawks and Redhawk revolvers. They are machined to match the special hook dovetail for these guns.
They give you the high visibility and precision of a fiber optic sight with the strength of our solid steel construction.
Distance Between Front & Rear Sights
Give yourself the extra height needed to match up your front sight with your rear sight along with maintaining the contour of your barrel. Choose the standard bead or a fiber optic front sight to dovetail into the Marble Arms® ramp. The ramp screws securely to your barrel with one 6-48 screw that is provided.
Ruger® Style Front Sights
Marble Arms® Fiber Optic Uni-Ramp Front Sights
Uni-Ramp Front Sights
Front Sight with Dovetail Ramp
Contour Front Sights
How to Use Table Above-Suppose a rifle, having a sighting radius of 24” between front sight and receiver sight, shoots 6” high at 100 yards, even with the rear sight adjusted as low as possible. Remove front sight and measure overall height, preferable with a micrometer. This might be .410”, such as a Marble No. 41MR. Reference to columns for 24” and 6” on table above will show a necessary correction of .040”. This would mean a new, higher front sight (with an overall height of .410” plus .040” for a correction height of .450”) such as a Marble No. 45MR, should be installed.
Sighting in should be done with a bench rest or prone with a sand bag or other rest for the rifle. Do not put rifle barrel or forearm directly on solid surface, but put the back of your hand or wrist on the rest and hold forearm of the rifle securely in your hand with approximately the same tightness of grip you would use when shooting at running game. If the firearm or barrel is rested directly on the sand bag or rest, the rifle will shoot higher than when held firmly while shooting at game as more “muzzle flip” will occur.