Marble Arms ® Rear Sights Gun Sight Specifications/Maintenance   Sporting Rear Sights   Short Blade1-7/8" Long (Step Elevator Included) Style Description Elevation Adjustment Mfg# Flat Top #63 .275”-.505” 006300 Flat Top #63H .350”-.630” 006301 Semi-Buckhorn #64 .275”-.505” 006400 Semi-Buckhorn #64H .350”-.630” 006401 Full Buckhorn #65 .300”-.510” 006500   Long Blade 2-3/4" Long (Step Elevator Included) Style Description ElevationAdjustment Mfg# Flat Top #66 .300”-.510” 006600 Flat Top #66H .350”-.630” 006601 Semi-Buckhorn #67 .300”-.510” 006700 Semi-Buckhorn #67H .350”-.630” 006701 Full Buckhorn #68 .300”-.510” 006800     Folding Rear Sight   Style Description Sight Height Mfg# Folding Sporting Rear #95 .320”-.420” 009500 Measure from bottom of Upright to bottomm of "U" or "V" notch.   Replacement Parts   Item Mfg# Notch Piece & Screw 000950 Double Step Elevator Short (Fits #63, #63H #64, #64H, #65) 009100 Double Step Elevator Long (Fits #66, #66H, #67, #67H, #68) 009200 Single Step Elevator (.050” Thick) 009050 Single Step Elevator (.080” Thick) 009080   Slot Blanks   Item Mfg# Slot Blank-Blued 001187 Slot Blank Nickel Plated 001188 Folding Leaf Sight   Style Description Sight Height Mfg# Flat Top #69 .360”-.460” 006900 Flat Top Folding #69H .460”-.560” 006901 Flat Top Folding #69EH .520”-.620” 006902 Windage Adjustable #69W .360”-.460” 006910 Windage Adjustable #69WH .460”-.560” 006911 Windage Adjustable #69WEH .520”-.620” 006912     Measure from bottom of Dovetail to Bottom of "U" or "V" notch.         Calculating Rear & Front Sight Height Combination 1. Measure the diameter of the barrel at the point of the rear sight upright and at the point of front sight bead (example: 1.00” rear sight and .750” front sight). 2. Divide the diameters by 2 (example: 1.00” /2=.500”). This is the distance from the center line of the barrel to the top of the barrel. 3. Check the rear sight height adjustment chart for the middle adjustment height (example: Large Low #20 sight adjusts from .420” to .520”). So .470” is the mid point. 4. Add the mid point adjustment to the center line distance (example: .470”+.500”=.970”). 5. Subtract the front sight center line figure from the rear sight height (example: .970”-.375”=.595”). 6. You need a combination of front ramp and front sight with the height of .595”. 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.     Distance Between Front & Rear Sights   Amount of Adjustment Necessary to Correct   14" 15" 16" 17" 18" 19" 20" 21" 22" 23" 24" 25" 26" 27" 28" 29" 30" 31" 32" 33" 34" *1” 0.0038 0.0041 0.0044 0.0047 0.005 0.0053 0.0055 0.0058 0.0061 0.0064 0.0066 0.0069 0.0072 0.0074 0.0077 0.008 0.0082 0.0085 0.0088 0.0091 0.0093 *2” 0.0078 0.0083 0.0089 0.0094 0.01 0.0105 0.0111 0.0116 0.0122 0.0127 0.0133 0.0138 0.0144 0.0149 0.0155 0.016 0.0156 0.0171 0.0177 0.0182 0.0188 *3” 0.0117 0.0125 0.0133 0.0142 0.015 0.0159 0.0167 0.0175 0.0184 0.0192 0.0201 0.0209 0.0217 0.0226 0.0234 0.0243 0.0251 0.0259 0.0268 0.0276 0.0285 *4” 0.0155 0.0167 0.0178 0.0189 0.02 0.0211 0.0222 0.0234 0.0244 0.0255 0.0266 0.0278 0.0289 0.03 0.0311 0.0322 0.0333 0.0344 0.0355 0.0366 0.0377 *5” 0.0194 0.0208 0.0222 0.0236 0.025 0.0264 0.0278 0.0292 0.0306 0.0319 0.0333 0.0347 0.0361 0.0375 0.0389 0.0403 0.0417 0.0431 0.0445 0.0458 0.0472 *6” 0.0233 0.025 0.0267 0.0283 0.03 0.0317 0.0333 0.035 0.0367 0.0384 0.040 0.0417 0.0434 0.045 0.0467 0.0484 0.05 0.0517 0.0534 0.0551 0.0567 *Amount of error at 100 yards is given in inches     Front Sight Elevation Correction Chart   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.   Return to Rear Sights Product Page     * Marble Arms does not sell customer direct. To find a retailer near you please visit our Distributor page.