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Posted: 5/7/2013 11:06:21 PM EDT
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Probably the best video I've ever seen, explaining what kinds of zeros you can employ.
[youtube]http://www.youtube.com/watch?feature=player_embedded&v=YUwve2VMFBU[/youtube] |
http://www.youtube.com/watch?feature=player_embedded&v=YUwve2VMFBU Good common sense video. If you can only zero at shorter distances, at least know what you are getting. |
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When you want to embed a YouTube video, copy the URL you see when you click on 'Share,' then paste that URL in the 'Flash' icon's 'Source' field. Here's what that URL looks like: http://youtu.be/YUwve2VMFBU I've found that using the URL of the YouTube page itself can produce odd results. |
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Quoted: I thought that a 50 yard zero and 200 yard zero were interchangeable? How come it's so much different in his video? I've always zeroed at 50 yards for a 50/200 zero. Shots at 100 yards are +2" POI Not sure why his 200-yard zero shows less delta up for the 100-yard POI. |
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Quoted: Probably the best video I've ever seen, explaining what kinds of zeros you can employ.  http://www.youtube.com/watch?feature=player_embedded&v=YUwve2VMFBUtheres a more detailed post at the top, where no one ever looks. You would be better off using the thread info, than some assumptions from the video. |
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Go to JBM ballistics and input your data, and change the zero around and watch what happens with it. Set you yardage for increments of one or two yards.
Generally what I have been doing with optics or sights that don't have a yardage marked on them, is to do a battle sight zero based on a 3 inch vital zone / point blank range of bullet that I shoot most. What that will do is give you a trajectory that your bullet will not go over or under 3 inches out to a certain distance. On the parameters, set the vial zone to 3 inches, and then click on the bottom to zero at point blank range. Use the 1 yard increments, and you'll see your short zero. I'm using three inches because I will take game with this rifle/optic. Meprolight M21 with triangle. If I was using it for defense only, I might open that up to a 4 or 5 inch vital zone, which would give me a hit without holdover at a further distance. For me, it looks like this for a 6.8, Hornady 110gr OTM at 2700fps. Zero is at 24 yards. 50 / +1.3 100 / +2.8 150 / +2.8 High point is +3 inches from 115 yards to 139 yards 200 / +1.3 Long range zero is at 261 yards. 250 / - 2.0 300 / - 7.3 400 / - 24.6 500 / - 52.9 |
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Quoted:
So if I zero at 50, (near zero) and then the bullet crosses over again to zero at 200, ....... How do I zero at 200? perhaps I'll watch this again after morning coffee... Go to JBM, and set your data up, enter 200 yards for your zero. If you set increments at 1 yard, it you will see your close zero. You can zero at that range and then also be zeroed at 200. The bullet crosses the line of sight twice, because the sights are above the bore, and the bullet falls due to gravity. You are actually aiming up above the bore so that the bullet rises. If you were to hold the barrel perfectly straight at 90 degrees to the ground, the bullet would never cross the line of sight, since it would be falling immediately. As the bullet rises it crosses, and as it drops it crosses again at some point downrange. |
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Quoted:
Quoted:
So if I zero at 50, (near zero) and then the bullet crosses over again to zero at 200, ....... How do I zero at 200? perhaps I'll watch this again after morning coffee... Go to JBM, and set your data up, enter 200 yards for your zero. If you set increments at 1 yard, it you will see your close zero. You can zero at that range and then also be zeroed at 200. The bullet crosses the line of sight twice, because the sights are above the bore, and the bullet falls due to gravity. You are actually aiming up above the bore so that the bullet rises. If you were to hold the barrel perfectly straight at 90 degrees to the ground, the bullet would never cross the line of sight, since it would be falling immediately. As the bullet rises it crosses, and as it drops it crosses again at some point downrange. This. The bullet is travelling in an arc. If no outside forces are acting on it besides gravity, it will be symmetrical in regards to it's max height. Any zero will work spot on at two distances, hence 25/300m and 50/200m zeroes. Regardless if you zero at 50 or 200, it will be zeroed for both distances. Zeroing at a closer distance is just preferred as it reduces spread so you can get a better read on where the rounds are hitting. |
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Quoted: Quoted: I thought that a 50 yard zero and 200 yard zero were interchangeable? How come it's so much different in his video? I've always zeroed at 50 yards for a 50/200 zero. Shots at 100 yards are +2" POI Not sure why his 200-yard zero shows less delta up for the 100-yard POI. Luck. The fact is, if he has a 1-MOA rifle, that the 200yrd hit can move as much as 1" from the actual ZERO point. SO it could be anywhere in a 2" circle. Maybe it hit higher than center, maybe lower. |
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`Decent video as far as illustrating zeroing concepts. The "holes" are generally correct but there are some errors. No telling what the holes were made with. Plus we don't know how high his optic is mounted. The 200 yard target would suggest an optic mounted around 1.75" above bore. Refer to a ballistics program using your data for actual POI.
The 100 yard target has some errors for the 25 and 50 yard holes; these should both be lower lower than the 100 yard hole. ============================================================ Sight Height makes a huge difference. 55gr - 3050fps - .243 BC - Zeroed for 200 yards. (sea level, 59degF, 29.92inHg) Sight Height 1.5" 50 yards = 0.67" high Sight Height 2.75" 50 yards = 0.28" low 62gr - 2925fps - .304 BC - Zeroed for 200 yards. (sea level, 59degF, 29.92inHg) Sight Height 1.5" 50 yards = 0.75" high Sight Height 2.75" 50 yards = 0.20" low ============================================================ |
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