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2/27/2007 11:25:03 PM EDT
heres my problem... i zero my personal weapons(ar15's) at 50 yds. and get a pretty flat trajectory out to 220 yds or so but i then i have to zero my duty M4 on the normal 25m, 300m army battle sight zero. now i know the correct hold over(or under) for the 300m bsz for human sized targets out to 300m. my question is how much hold over on the 50yds ibz do i have to do in order to engage targets out to 300m (and beyond)? FYI i have a 16in. barrel 1-9 twist and i use lake city m855 and my rear sight is a arms #40 (or A1 type)
2/28/2007 2:22:27 AM EDT
[#1]
Well, using the 50yd IBSZ (which I happen to like) at 220 yds the bullet has already begun it's downward trek and is @ 2" below line of sight. A quick glance at a reloading manual shows you'd be @ 8" below line of sight at 300yds (6" more than you were at 220yds). So a holdover of 8" SHOULD smack it dead center at 300.

This where a ballistics calculator comes in handy. You can work up holdovers/unders for any caliber, barrel length, height above bore, etc.  

HTH
2/28/2007 3:08:34 AM EDT
[#2]
I thought you had to turn the elevation to compensate for distances at 300m, 400m, 500m, 600m, etc? The whole point of the IBZ was to get a flat trajectory out to 200m using the small aperture, nose to charging handle, wheel bottomed out, and then turn the wheel 2 or 4 clicks up to the 8/3 or 6/3 mark respectively for 300m targets. It's not a perfect zero but should be minute of person.
2/28/2007 3:54:45 AM EDT
[#3]
height=8
Quoted:
I thought you had to turn the elevation to compensate for distances at 300m, 400m, 500m, 600m, etc? The whole point of the IBZ was to get a flat trajectory out to 200m using the small aperture, nose to charging handle, wheel bottomed out, and then turn the wheel 2 or 4 clicks up to the 8/3 or 6/3 mark respectively for 300m targets. It's not a perfect zero but should be minute of person.


exactly

you shoot 0-200 with your sight bottomed out -2/-4 (unless you using the big aperture)  when you start getting into ranges like 300/400 etc you click to the various elevations

simple
2/28/2007 11:16:45 AM EDT
[#4]

Quoted:

Quoted:
I thought you had to turn the elevation to compensate for distances at 300m, 400m, 500m, 600m, etc? The whole point of the IBZ was to get a flat trajectory out to 200m using the small aperture, nose to charging handle, wheel bottomed out, and then turn the wheel 2 or 4 clicks up to the 8/3 or 6/3 mark respectively for 300m targets. It's not a perfect zero but should be minute of person.


exactly

you shoot 0-200 with your sight bottomed out -2/-4 (unless you using the big aperture)  when you start getting into ranges like 300/400 etc you click to the various elevations

simple


OK, so what adjustments do you make if you flip to the big aperature?
2/28/2007 11:56:34 AM EDT
[#5]
i understand that when you engage target out to 300yds you use the elevation wheel but my question is regarding A! type sights with no elevation wheel. does anyone know a link to a good ballistic calculator?
2/28/2007 12:37:02 PM EDT
[#6]

Quoted:
i understand that when you engage target out to 300yds you use the elevation wheel but my question is regarding A! type sights with no elevation wheel. does anyone know a link to a good ballistic calculator?


I think the poster above answered your question with - 8 inches -  No adjustments necessary, nor possible with your Arms 40

www.norma.cc/htm_files/javapagee.htm

That's a good calculator, just define the bullet your using.  
2/28/2007 12:48:10 PM EDT
[#7]
how do i define my bullet? whats ball coefficient? i shoot lake city M855 62gr. FMJ
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