- Thread starter Barn Side
- Start date
The Math:
One MOA is 1.047 inches at 100 yards.
100 yards is 3600 inches.
1 MOA is 1.047"/3600 per each inch of length or 0.000291"
20 MOA is 1.047 X 20 at 100 yards or 20.94"
20 MOA is 20.94"/3600 per each inch or 0.005817" per each inch.
20 MOA is 0.005817" X 4 for 4" of rail or 0.0233"
20 MOA is 0.005817" X 6 for 6" of rail or 0.0349"
Zero MOA has no slope on the rail.
No Algebras were harmed with this calculation
One MOA is 1.047 inches at 100 yards.
100 yards is 3600 inches.
1 MOA is 1.047"/3600 per each inch of length or 0.000291"
20 MOA is 1.047 X 20 at 100 yards or 20.94"
20 MOA is 20.94"/3600 per each inch or 0.005817" per each inch.
20 MOA is 0.005817" X 4 for 4" of rail or 0.0233"
20 MOA is 0.005817" X 6 for 6" of rail or 0.0349"
Zero MOA has no slope on the rail.
No Algebras were harmed with this calculation
Last edited:
Measure the height of the front, the height of the back, and the length. Use your preferred inverse trigonometric function to solve for the angle.
Example:
arctan( (back height - front height) / (length) )
Example:
arctan( (back height - front height) / (length) )
That works too
Example,
0.4 inch at back, 0.3651 inch 6 inches away at front.
.4-.3651 = 0.0349, divided by 6 = 0.005817.
arctan of 0.005817 = 0.333327 (degrees)
x 60 = 19.996 Minutes
20 MOA
Measure to one thousandths?
0.4-.365 =0.035, divided by 6= 0.005833.
arctan of 0.005833 = 0.334222 degrees.
X 60 =20.053 Minutes
20 MOA
and the Algebras escaped unscathed again
Example,
0.4 inch at back, 0.3651 inch 6 inches away at front.
.4-.3651 = 0.0349, divided by 6 = 0.005817.
arctan of 0.005817 = 0.333327 (degrees)
x 60 = 19.996 Minutes
20 MOA
Measure to one thousandths?
0.4-.365 =0.035, divided by 6= 0.005833.
arctan of 0.005833 = 0.334222 degrees.
X 60 =20.053 Minutes
20 MOA
and the Algebras escaped unscathed again
Last edited:
Note that you don't have to measure the entire length. It is sometimes difficult to measure the thickness due to an overhang beyond the mounting holes and such. So just measure the length at the point you measured the thickness and any of the above methods still apply.
Ouch! My brain hurts.
- Nov 3, 2010
- 8,645
- 17,544
Here we go, gonna hurt the Algebras solving for a.
I measure from the top to the bottom of the last pic scope rail at the chamber end (top image) getting 1.4 Inches. Next I measure from the top of the last pic rail to the bottom of the barrel (bottom image) getting 4.8 Inches. Finally I measured just the barrel diameter right in front of the pic rail (bottom image) getting 3.4 Inches. I subtracted the barrel diameter from the rail and barrel (4.8-3.4) and got 1.4 Inches. That’s the same as the other end, so I’m thinking this is a 0 MOA pic scope rail on my Blaser tac 2 in 223. This has me totally confused since my serial according to XTEK had 30 MOA or retrofitted versions with 50 MOA. Then according to Blaser it is 20 MOA. Finally I saw EuroOptic sold them in 223 with either 12 MOA or optional 40 MOA. 
Measure the height of the rail to the barrel at the front, and rear, and the distance between thr 2 measured points.
In this example i used 150mm apart, and the difference (or measured angle) is 0.87mm. Say you use a vernier and measure 10.5mm at one end, and 11.3mm at the other end.. you have a 0.8mm difference.
Plug that data into the triangle calc.
BAM !! (Then convert degrees to MOA)
I’m getting no difference between the height of the front and back of the scope rail using calipers (when measured as above). Any gurus see anything wrong in how I measured? And anyone ever heard of a Blaser Tac 2 with a 0 MOA scope rail?
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