Rawson Sight - Event Date: August 29 2014 |
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mungo
Groupie Joined: July 23 2011 Location: Australia Vic. Status: Offline Points: 36 |
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Posted: August 28 2014 at 3:47pm |
I have just bought a very nice Rawson aperture sight to fit to my No.1 Mk.III. I'm having trouble understanding the distance scale on the side plate. I can see that the markings on the left of the scale are in 100yd. increments. The markings on the right of the scale are I think some sort of vernier arrangement. But I can't make any sense of it. Can anyone explain the operation of this sight to me. Preferably in terms that an idiot can understand. Thanks.
mungo.
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DairyFarmer
Senior Member Joined: July 19 2014 Location: In The South Status: Offline Points: 555 |
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Don't know the sight, but it sounds very much like reading decimals on a vernier calliper or beam scale.
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mungo
Groupie Joined: July 23 2011 Location: Australia Vic. Status: Offline Points: 36 |
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Yes, I'm sure it operates on that kind of principle, but I can't get the lines on the right to make any sense.
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muffett.2008
Senior Member Joined: December 09 2011 Location: scone. nsw Status: Offline Points: 751 |
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The sight scale is marked in Yardage for Mk.VII ammunition (unless stamped 7.62) the finer scale is in points of an inch for more accurate range usage.
With the rifle zeroed at 300yds, the scale plate is zeroed so that so the scale on the left reads 300, the right scale will now have the base line at zero, as this sight is in half minutes(2 clicks to a point or minute of angle) if we want to move the sight to the 200 yard mark ( left 3 and a 1/2 points) we would wind the sight 7 clicks anti clockwise. Knowing our target elevation settings in minutes for the ammunition we are using, allows us to adjust rapidly for that range(which will vary from the elevation scale as we are not using the milspec ammo) and then fine tune our elevation to maintain centre during our shoot. |
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mungo
Groupie Joined: July 23 2011 Location: Australia Vic. Status: Offline Points: 36 |
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Thanks for the reply muffett. I appreciate the effort you've gone to. I'm a bit closer to grasping it, but the figures don't make sense to me. This is my reasoning. With the scale on the right, 10 clicks will give you 1" of movement. So 1MOA @ 300yds is 3", and 1MOA @ 200yds is 2". Would that not mean that from a 300yd rifle zero, you would move the scale 10 clicks down, to get 200yds. Not 7 and a half clicks down. What am I missing ?
mungo
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DairyFarmer
Senior Member Joined: July 19 2014 Location: In The South Status: Offline Points: 555 |
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Rule of thumb for click.
From your point blank range, at half the distance you double the click to adjust. At double the distance you half the clicks. Say your sight are 1 click = 1/4" @ 100 meters. Then at 200 meters 1 click = 1/2" and at 50 meters 1 click = 1/8". BTW for the uninformed or mislead by the media: Point Blank Range = the point/s at a bullet crosses the sight line. In other words the distance that you zero your sights. It DOES NOT mean really close, unless someone was stupid enough to zero their firearm at < 1 meter. |
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muffett.2008
Senior Member Joined: December 09 2011 Location: scone. nsw Status: Offline Points: 751 |
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No, 1 point equals 1 inch, the diagram (figure 20) shows the vernier scale at zero, all the lines match. To adjust 1 moa, irrespective of distance, you would move the sight up or down 2 clicks(1 point), therefore that 1 point would equal 1inch at 100, 2 inches at 200 and so on.
The second pic on right in figure 20 shows the adjustment for 5 points of elevation(10 clicks), note that the vernier now shows the first line-zero(each line equals 5 points) in line with the first segment.
Now to read a lesser amount, say 2 points, the 2nd line from zero will now be in line with the 2nd line (10 on the 0-80scale) showing the sight is set at 2 points. One of the failings of the Rawson sight is the lack of zero marks, leading to confusion for the novice, but once understood, the sight scale is reasonably accurate, on a par with British sights but reading only about 80% in relation to other Aussie sights. Look at the diagram on reading the vernier scale, it is self explanatory, you also apply the same principle to windage,(at least this has a zero/zero line), just turn the sight on it's side and look at half the scale, you will see that it is a duplication of the vertical scale, with the zeros lined up you have 5 graduations to the 20 point mark, as each point is wound on, a different line will match up, practice, you will work it out. |
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mungo
Groupie Joined: July 23 2011 Location: Australia Vic. Status: Offline Points: 36 |
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Thank you muffet. Got it now.
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