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Posted: 3/19/2006 5:02:26 PM EDT
i finally got my first ar out to the range, and i got dialed in for 50 yds...

i had a challenge from a friend that was with me, he wanted to go 5 shots at 100 yds.

i never pass up a challenge so we went for the ghusto, i was on at 50 yds, and landed about 4" high, is this normal?

for what its worrth, i waxed his ass with 3 of 5 touching one another.

thanks for the ballistics info....
Link Posted: 3/19/2006 5:38:50 PM EDT

Originally Posted By stoutshooter:
i finally got my first ar out to the range, and i got dialed in for 50 yds...

i had a challenge from a friend that was with me, he wanted to go 5 shots at 100 yds.

i never pass up a challenge so we went for the ghusto, i was on at 50 yds, and landed about 4" high, is this normal?
for what its worrth, i waxed his ass with 3 of 5 touching one another.

thanks for the ballistics info....




How was that again? You zeroed your rifle at 50 .... and were you hitting 4" high at 50? Or 4" high at 100?

If it's the latter, then it's normal to have a POA / POI difference if you are dialed at 50and shoot 100.
Link Posted: 3/19/2006 5:41:50 PM EDT
[Last Edit: 3/19/2006 5:42:51 PM EDT by JL7]
I take it as he was sighted in at 50 and was 4" high at 100, which as you said is normal

ETA: grammer
Link Posted: 3/20/2006 9:24:46 AM EDT
yeah that is what i ment

thank you for the grammer and the answer
Link Posted: 3/20/2006 11:34:09 AM EDT
If you're sights are at the proper (2.6") height then your groups should be centered roughly 2" high at 100y (and with a 4moa group that means some will hit 4" high and some will hit spot on at 100y)..

If you've got an optic mounted on top of the carry handle then 4" is not unreasonable.
Link Posted: 3/21/2006 6:06:59 PM EDT
i have a variment rig with a 20" bull barrel and a 50mm objective scope on a fla t top upper


Also, the guy i was shooting with says he had the same trouble, he was shooting an ar with a 16" barrel at 7.62X39

he claimed to be shoting high at 100 when sighted in for 50


sound right??

thanks
Link Posted: 3/22/2006 7:32:08 AM EDT
[Last Edit: 3/22/2006 8:34:11 AM EDT by Forest]

Originally Posted By stoutshooter:
i have a variment rig with a 20" bull barrel and a 50mm objective scope on a fla t top upper


How high are your rings? A 50mm objective is pretty big.

I just ran some numbers even with the scope mounted at 3" over bore, with a MV of 3250 you should only be 2.1" high (assuming standard conditions at 1400' ASL)



Also, the guy i was shooting with says he had the same trouble, he was shooting an ar with a 16" barrel at 7.62X39


I don't have any 7.62x39 data in front of me (I'd need MV, bullet weight and BC). but I'd expect it to shoot within 2-3" high at 100y if it was zeroed at 50y.

You guy's aren't zeroing one way (say offhand, or using a sling) they doing your shooting using a bipod or sandbags? If the barrel sin't free floated you can deflect the barrel downward using a sling, and upward using sandbags or bipod near the FSB.
Link Posted: 3/22/2006 8:31:46 AM EDT

Originally Posted By stoutshooter:
Yeah that is what I meant.

Thank you for the grammar and the answer.


Fixed it for you.

Does "stoutshooter" refer to your shape or your school? My dad taught at UW-Stout for 35 years.
Link Posted: 3/22/2006 9:13:41 AM EDT
Even with high rings there shouldn't be that much parallax from 50 to 100, right? The bore - sight relationship isn't any worse than with iron sights... Depending on the quality of scope, you may have some issues. That should be less than a minute of adjustment, for sure.

Were you in the center of the adjustment range or toward one end or the other for your elevation?
Link Posted: 3/22/2006 9:27:18 AM EDT
something to remember is that the if the arc of the bullet passes through your sight plain at 25...then it will pass back through at 250...the bullet arcs up
Link Posted: 3/22/2006 9:33:42 AM EDT

Originally Posted By RRA0211:
something to remember is that the if the arc of the bullet passes through your sight plain at 25...then it will pass back through at 250...the bullet arcs up



Where do you people come up with this crap!?

I can assure you if the bullet from an AR-15 is POI=POA at 25y (or meters) it most assuredly will NOT be passing through the POA at 250.
Link Posted: 3/22/2006 9:34:07 AM EDT
I'd rather Zero at 100 and Hit 1" or so low at 50. But I guess I like things too simple.
Link Posted: 3/22/2006 9:41:06 AM EDT
Parallax is an optical effect where the relationship between crosshairs and target can shift if he moves his eye around behind the scope w/o moving the gun. If he has a good repeatable cheek weld it'll be minimal (and it usually is anyway).

He's talking about the trajectory arc, which would depend on the bullet, velocity, and height of the sights. Iron vs. scope wouldn't matter if they're at the same height. As Forest noted, if it's sighted for 50yds it'll shoot high at 100yds. That's normal.
Link Posted: 3/24/2006 7:48:03 AM EDT

Originally Posted By Forest:

Originally Posted By RRA0211:
something to remember is that the if the arc of the bullet passes through your sight plain at 25...then it will pass back through at 250...the bullet arcs up



Where do you people come up with this crap!?

I can assure you if the bullet from an AR-15 is POI=POA at 25y (or meters) it most assuredly will NOT be passing through the POA at 250.


you will have to excuse my mistake i read it wrong
Link Posted: 3/27/2006 6:38:52 AM EDT
2.4cm = 0.945" low at 25m and dead on at 25m are not the same sight setting.

2.4cm low does come back on at 250m, after being 3" high
zeroed at 25m comes back down at 365m, after being 10" high
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