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Scope subtensions

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deaddog View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote deaddog Quote  Post ReplyReply Direct Link To This Post Topic: Scope subtensions
    Posted: 11 June 2017 at 04:09

Is their a way to easily at close range figure out the duplex subtensions
of a scope? For example most Leupold's are 18" at the highest power
setting. They publish this info. What about other brands that don't
publish or are out of business? Can you put up a board at 10' or 10
yards and do some sort of measurement and calculate from that?


DD
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BEAR View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote BEAR Quote  Post ReplyReply Direct Link To This Post Posted: 11 June 2017 at 06:53
Cb is Mr sub-tension.

I think all you need to do is push a yard stick into
the ground at say 50 yds. with the crosshair on the
end (zero inch) see where the sub tension point/line
is. then linearly scale up ie double at 100yd and
double that for 200 yards, etc.

most people are using that tension for drop when
distance is long, so power is max. so that is where
I'd calibrate, at max power.

personally I use Kentucky windage/elevation out to 300
yards...beyond that a better hold point can help.

I like at 50 yards, but 10 yds would work also...but
more difficult to read that smaller number.

just thoughts
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Post Options Post Options   Thanks (0) Thanks(0)   Quote RobertMT Quote  Post ReplyReply Direct Link To This Post Posted: 11 June 2017 at 16:00
If you're wanting to know distance across, from thicker part of post to thicker part of post? I would think if you measured from center of cross hair, to one side and doubled it, you would be most accurate. If you can't read to 1/4"s on yardstick at 100yds, go to fifty and quadruple it. The closer you read it to 100yds, normal distance parallax is set to, in hunting scopes, the more accurate.

So if you get 4 1/2" @ fifty yards @ 9 power, you would have 4.5 X 4 = 18" @ 100yds @ 9 power, 4.5 x 4 x 5 = 90" @ 500yds @ 9 power, 4.5 x 4 x 3.75 = 67 1/2" @375 yds @ 9 power.

I think most scopes are close to this, I learned shooting /06 @ 500yds hold thick point of post, @ 6 o'clock hold, like iron sight and you would be good. This would give you 45" of elevation, about perfect for 2" high @ 100yds, we always zeroed at. We weren't allowed to start hunting, until we could put five rounds, in center 6" of paper plate @ 500yds, from field rest (across daypack on rock or prone) every time.

You could go to 10yds, if you could adjust parallax and focus that close and measure to 1/16ths and multiple by 20. If my scope could read to 1/4" @ 50yds on 9 power, I'd be replacing it.

Of course metric would be even simpler calculations.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote deaddog Quote  Post ReplyReply Direct Link To This Post Posted: 12 June 2017 at 09:31
I think I can use that formula. I was out yesterday with my tri-pod set at
36". 18"x2 and drove out to 400 yards on the golf cart and worked back
in testing every 100 yards. I'll try again at 50yards. My scope has a
triple plex. Thin wires, a medium, and thick posts.

DD
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