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Post by zr600 on Feb 4, 2017 11:17:38 GMT -8
Ok what works the best for shooting of a bench for an ar15? I have been using a Caldwell leadsled but have to wedge a glove or something underneath the buttstock so the grip isn't touching the middle bar of the rest. So I have been wondering if there is a better more stable way this shoot my ar for load development and sighting in. Also I have a vortex viper pst and can't seem to get the parallax adjusted right. I have played with it a bunch and look through the scope and the reticle moves all over. My loads seem to group good one day then next time not worth a darn. I think I'm having some parallax issues what can I do for a test to check and see if that is what the issue is. My load shot like 1/2" when I developed it not it will be 2 touching then 2 touching and inch to the left then one 1.25 low. Then at 200 yards it was like 3". Now if my original load during development shot .3" would that open up that much at 200 yards or should I be testing loads out further? My range only has out to 200. Can adding vet wrap around the barrel and gas block affect anything? Any help would be great this is a 6x6.8 22" bull barrel.
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Post by Deleted on Feb 4, 2017 12:08:26 GMT -8
I use a Harris bipod, mounted on a stud on the free float, and a small bag in the rear that I can move back and forth and give a squeeze. Rear sling stud removal a must on a GI butt stock.
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Post by peabody on Feb 4, 2017 13:22:49 GMT -8
I've only ever shot off bags - always front, sometimes with a rear for additional stability. I see the idea behind using a sled. But I think it's a crutch, of sorts, to improve accuracy without improving one's shooting ability. If you're using it for load development, it's a good means for eliminating variables that can confuse accuracy. Aside from that, I see them as voodoo improvements that leave a shooter feeling more capable because the shooter has removed the shooter from the accuracy equation. Where's the challenge in that? Stepping off my soap box, I think a sled can pose a problem with parallax because the cheek weld will be different than that obtained by holding the rifle yourself. If you're changing any aspect of your cheek weld, you're changing the dynamics of the eye box and image alignment: setting the eye farther away from the ocular lens, rotating your head more to get aligned with the scope, etc - they all create a different image view than you'll get holding the rifle in a traditional manner. Now I'm not saying that will be an outright problem with accuracy. The two are separate issues. If you mount your rifle in a sled, strap it down, get the scope aligned with the paper and fire a group without the sled moving, your POI/group will best-represent the accuracy of the rifle with that given load. However, if you're using the sled to zero, your POI will likely shift to some degree when you switch to shooting with a traditional hold. And all of the human factors that the sled removes will come into play too, which leads many, myself included, to chase the ghost of accuracy and look for external factors which degrade accuracy when the problem is really the capability of the shooter. Regarding parallax itself, it's more of an issue of focus and optical alignment. Parallax adjustments help bring the image in focus with the sight plane. The range markings on your optic are somewhat subjective. A clear focus of the target is what you're looking for, in relation to a clear focus of the reticle, which should be set with the ocular focus (i.e. focus the reticle with the eyepiece, then focus the image with the parallax adjustment). The alignment aspect is a "global system" alignment of the optic's lenses and your eye (the last lens in the system). The alignment component is why I brought up the issue with the sled and parallax. You won't get the same alignment from a sled as you'll get from a hand hold. All that noted, the amount of POI shift induced by parallax is actually quite small at normal shooting ranges. It's only when you factor in super-high magnification with very long ranges that the effect will become more critical. I recall reading that the POI shift can be something like 12 inches at 1000 yards, depending on magnification used and how far off the parallax setting is (i.e. 100 yard parallax correction used for a 1000 yard shot). But take that last bit with a grain of salt... Here's a link to a short video that explains parallax very well in layman's terms: www.youtube.com/watch?v=1VPGcq9IVxcAnd a link to a good, but detailed technical discussion on parallax: www.opticstalk.com/what-exactly-is-parallax-anyway_topic5026.htmlOne more link to a technical description... read post #4: www.longrangehunting.com/forums/f18/parallax-vs-focus-1988/
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Post by chesapeake on Feb 4, 2017 19:47:22 GMT -8
I didn't read/ watch the links.......
If your scope has parallax adjustment then look at a light background or the sky ect.. and focus the reticle with the eyepiece focus. Once done this setting should be good. Then set your magnification power if adjustable. Then aim at a target at your desired range. Move your head up/down or left/right without moving the gun. You just need to move slightly. If the reticle moves on the target then adjust the parallax until it doesn't move. As you get used to making the adjustment you'll learn to wiggle your head while you turn the parallax adjustment to bring it in. The rifle needs to remain steady while you move your eye position. The scale on scopes is often off, but usually not too much.
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Post by zr600 on Feb 4, 2017 20:52:28 GMT -8
I guess I never used the sky for doing the reticle focus but I move my head very slightly and adjust and can only get it a little better there still a good bit of movement. On a target with the 1" circle when u center it and then move your head very slightly it will be off the circle. And that's the best I can get it. I'm guessing that's why I can't consistently get my great group the gun has had before which was a different scope. Think I'm going to be contacting vortex.
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Post by chesapeake on Feb 4, 2017 21:42:18 GMT -8
If you try and focus the reticle while looking at a close-ish object your eye may try to focus on the object, not the reticle. Using the sky or a distant bland background allows the eye to key in on the reticle alone. If you can't remove the parallax your scope likely has some internal lense alignment issue. Vortex should fix you up.
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Post by chesapeake on Feb 4, 2017 21:49:12 GMT -8
One more thing you could try. Get the parallax as good as possible with the parallax adjust. Then try and remove the rest with the eyepiece focus. If you can and keep everything in focus then maybe the eyepiece was way off.
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