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How to measure scope sight height |
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samchap
.416 Rigby Honor, Integrity Joined: 12 August 2003 Location: United States Status: Offline Points: 1781 |
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Posted: 11 September 2016 at 12:38 |
I'm going to do something I should have done years ago.
That is sight in my Win 70 for a zero at 200 yards or so. I shoot rem core-lokt 150 grain PSP and have always sighted in for 1" high at 100 yards and called that good enough for what distance I was normaly shooting to. This fall I will be trying some bogs that just might push me to 200 yards plus. I have been looking at ballistic trajectory charts and what I have seen so far are based on 1.5" or 2" sight height. Question: How is sight height determined? What I am looking for is being able to hold dead on and `be within + or - 3"-4" of that. I guess a follow up question would be, Does it make that much of a difference? I am going to get a range finder for the bog hunting for the obvious reason. I think using that will be a confidence builder. I've never hunted in the open before so this is going to be a fun thing for me. Yes I've seen the 'yote pictures and all I can say is that open has different meaning depending on your location. Kinda like what hot means to someone who can drink Texas Pete and what hot means to someone who never goes beyond a few drops of Tobasco Sauce and sauce and calls that hot enough. |
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samchap - Waldoboro, ME
Be careful what you decide to not like. Your wife may wear one. Your son may ride one. Your daughter may bring one home. You may have to have one someday. |
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Irish Bird Dog
.416 Rigby Too many Joined: 01 March 2009 Location: Midwest Status: Offline Points: 5511 |
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Samchap for the record are you going to be hunting "bogs" or HOGS???
I'd guess a Bog would be easier to hit than a HOG so less precision would be needed if you are indeed Bog hunting. |
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Irish Bird Dog
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CB900F
Administrator Honor, Integrity Joined: 10 June 2003 Location: Eritrea Status: Offline Points: 8857 |
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Samchap;
Do you have, or have access to, a chronometer? Unless you can determine the speed of the bullet to a reasonable state of accuracy, all trajectory charts etc., are just educated guesswork. However, having the experience with the .30-06 & 150 grain bullets that I do, if you don't have a chrono go three inches high at 100 yards. Using the online JBM ballistic calculator, I gave a muzzle velocity of 2850 fps with a 150 grain spitzer bullet & used a B/C of .377 - which would be typical & I found it in the Speer manual. I then said that the vital zone diameter was 6 inches. That gave me, and my experience confirms it, the following: +3" at 100 yards. +2.6" at 200 yards. -3.6" at 300 yards. So, your maximum point blank range is 282 yards. Point blank zero is 242 yards. In other words, put the crosshairs on it at any range up to 282 yards & under ideal conditions the bullet will not impact up or down more than three inches from the crosshair sight point. The 3" high at 100 really should work very well for you at any reasonable range you've told us you'll encounter. 900F |
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Birth certificate!? He don't need no steenkink birth certificate!!
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RobertMT
.416 Rigby Joined: 12 March 2008 Location: United States Status: Offline Points: 4413 |
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Sight above bore, is center of scope to center of bore, I just eyeball using a ruler, alongside bell of scope and bore, it'll get you close enough.
It matters, but under 500yds isn't critical. Either two inches high at 100yds, for under 250yds or three inches high, for up to 300yds work. The trouble with three inches high, is at 150yds or so, you'll be 4" high and if you need to thread the needle or take neck shot, it can matter. I find it easier to remember to hold high, than low. |
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samchap
.416 Rigby Honor, Integrity Joined: 12 August 2003 Location: United States Status: Offline Points: 1781 |
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IBD...BOGS as in a wet place with open water in places but
mostly grass and moss hummocks and cranberries..... You agigator. CB...I've been to these bogs before and 200 yards is the most distance I expect to shoot at but I was not thinking of hunting them when I was there so a range finder might be more accurate than my memory. R.MT...Thanks, that will work just fine. |
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samchap - Waldoboro, ME
Be careful what you decide to not like. Your wife may wear one. Your son may ride one. Your daughter may bring one home. You may have to have one someday. |
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BEAR
Administrator Joined: 07 September 2013 Location: Appalachian Mtn Status: Offline Points: 13734 |
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A Bog is a place where dying moose like to go!
I like 2" high at 100 yards, for the reason that Robert said. that way If under 200 yards it is right on. When I see a 300 Yard shot, I know it is a far shoot and just 'hold over' 6 inches. Long shots usually give me time to think, and figure the hold over. Short shots often don't give one time to think about trajectory. Re: scope height. I have a wooden ruler, and just set it on the top of the stock beside the scope (that is about the bore center line. Then measure up to the center of the tube. seldom a perfect 1.5 or 2 ". |
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