still puzzled

rebs · August 27, 2013, 04:33 PM

My Ar is sighted in at 100 yds perfect. But when I shoot at 50 yds I am 1" low and 1" to the right. The scope is mounted perfectly. I am shooting the exact same handload at both distances. It was on a perfectly calm day with zero wind. I understand a difference in elevation, but why the difference in windage ?

JimDandy · August 27, 2013, 04:40 PM

Was the barrel the same temp?

Same rest?

Were you ON the barrel? Either with the Rest or with your hand/sling etc.?

higgite · August 27, 2013, 05:05 PM

Parallax?

snuffy · August 27, 2013, 05:44 PM

Quote:

Parallax?

BINGO! Unless your scope is parallax compensated, AND you had it set correctly, you could easily be off an inch between 50 and 100 yards.

rebs · August 27, 2013, 05:44 PM

the barrel should have been the same temp since I shot the same number of shots starting with a cold barrel. I use the same rest under the hand guard, no sling.

Bart B. · August 27, 2013, 06:26 PM

Try shooting at 100 again then shoot at 50. There's a good chance you're not shouldering and holding the rifle the same at each distance.

Brian Pfleuger · August 27, 2013, 06:27 PM

Wind (or lack thereof) could theoretically account for the difference in windage but being 1" low at 50 will never ever get you to zero at 100.

243winxb · August 27, 2013, 06:47 PM

The difference in windage may be caused by the scope being off axis. The perfect example of off axis, is a side mount on a Win. M94. The scope has to be directly over the bore and the scope adjustment should not be much off from its center setting. As far as shooting low at 50 yds with a 0 at 100, common when the scope is mounted high. IMO.

Swampman1, I Sold it- Tranfer was approved on July 28, 2011,

Swampman1 · August 27, 2013, 07:10 PM

243, me likes that rifle...wanna trade for my Colt LE6920?

rebs · August 29, 2013, 05:52 AM

My scope is mounted a little high as it is on 1/2" risers with see through mounts to get it high enough for a good cheek weld. If I just use the see through mounts without the 1/2" risers then it is hard to get my head low enough on the stock. Its a flat top AR and the scope is about the same height as where the iron sights are with the carry handle on it.

Jimro · August 29, 2013, 06:00 AM

If you zero at 100, the bullet is "rising" up until that point with most loads for 223. Combine that with a high scope and it is easily 1" low at 50.

Most scopes are set to be parallax free at 100 and beyond, so you have to hold your eye in the same spot every time to make the same shot every time.

Jimro

243winxb · August 29, 2013, 08:48 AM

Quote:

If you zero at 100, the bullet is "rising" up.

Sure is. If the barrel is parallel to the ground, the bullet starts dropping almost as soon as it leaves the barrel. The barrrel has to be pointed up to hit the target at 100 yds. This has the bullet rising upon exit of the barrel.

higgite · August 29, 2013, 10:13 AM

Jimro is right, a typical AR zeroed at 100 yds for a typical 55gr FMJ load will print about 1" low at 50 yds. So, you have no problem elevation wise.

If your rig is truly zeroed for windage, then it's zeroed for all distances. Gravity doesn't work sideways.

Disregarding parallax, if it's truly shooting 1" wide at 50 yards, it would be 2" wide at 100 yds.

I'm still going with parallax as the cause for your wide POI at 50 yds. What scope are you using? Is it parallax adjustable?

JimDandy · August 29, 2013, 10:27 AM

Quote:

243, me likes that rifle...wanna trade for my Colt LE6920?

Whats wrong with your 6920? I love mine to death.

Brian Pfleuger · August 29, 2013, 10:27 AM

Ok, if you've got your scope about 3-3.5 inches above the bore, you could be at 1" low at 50 with a 100 yard zero. Any lower and you're going to have to be at 2,900 fps or less to get 1" low at 50 with a 100 yard zero.

At that point, you're "zero" is essentially from 92 to 111 yards, within 0.1", and you'd be zeroed again at 166 yards and within 0.1" from 157 to 175.

MJFlores · August 29, 2013, 11:16 AM

Bullets dont rise...they're shot upward on an arc sometimes.

Jim243 · August 29, 2013, 03:19 PM

Reply #3 & #4 gave you the answer. Parallax! You are not looking at the same spot at 100 yards and 50 yards. The distance has changed between your eye and the cross hairs (actually the angle). You will need to get a parallax correcting scope (AO) or a low fixed power one (4x) set at the factory set to 100 yards.

Jim

rebs · August 29, 2013, 03:39 PM

My scope is a Leupold 3-9 x 40, there is no parallax adjustment, only the eye piece, elevation and windage. I had read in an article on the internet that by using a spanner wrench you can turn the objective lens to change the parallax adjustment, I never tried it and don't know if it true or not.
With my eyes closed I bring the rifle up to my shoulder and open my eyes and the scope is right there, I see the full circle of view. I believe my eye is always the same distance from the eye piece on the scope. Maybe I am wrong and will check when I go to the range tomorrow.

Jim243 · August 29, 2013, 03:55 PM

When you change the power, you are moving the recital to or from your eye. Not a lot, but you were talking about a 2 MOA distance at 50 yards (1 inch).

The distance from your eye is different between 100 yards and 50 yards, so yes the recital is moving in relation to your retina. (your eyeball changes shape) My suggestion is to set your zero at the distance that you will shoot the most, say 50 yards or 75 yards and you should then be within a reasonable zero anywhere between 50 to 150 yards.

I would not take a wrench to that scope. Just set your zero to the distance you shoot the most.

Jim

Swampman1 · August 29, 2013, 04:42 PM

Quote:

Whats wrong with your 6920? I love mine to death

Jim I've had mine barely a month now, and I love mine too! But I would love to have a full auto as well.

Too bad it's almost impossible to own one here.

balderclev · August 29, 2013, 05:37 PM

I zero all my centerfire rifles at 200 yds. I first start at 25 yds and set it at 1.5" low followed by 1.5" high at 100 yds. That puts me close to zero at 200 yds.

Horizontal or windage is not affected by your scope at different distances.

I would suggest that you zero it at 1.5" low at 25 and then shoot at 100 or 200 yds. Anything variance horizontal is either because of lack of zeroing at 25 or a problem with your platform or holding.

August 27, 2013, 04:33 PM	#1
rebs Senior Member Join Date: January 10, 2012 Posts: 3,881	still puzzled My Ar is sighted in at 100 yds perfect. But when I shoot at 50 yds I am 1" low and 1" to the right. The scope is mounted perfectly. I am shooting the exact same handload at both distances. It was on a perfectly calm day with zero wind. I understand a difference in elevation, but why the difference in windage ?

August 27, 2013, 06:27 PM	#7
Brian Pfleuger Moderator Emeritus Join Date: June 25, 2008 Location: Austin, CO Posts: 19,578	Wind (or lack thereof) could theoretically account for the difference in windage but being 1" low at 50 will never ever get you to zero at 100. __________________ Nobody plans to screw up their lives... ...they just don't plan not to. -Andy Stanley

August 27, 2013, 06:47 PM	#8
243winxb Senior Member Join Date: July 26, 2011 Location: USA Posts: 1,730	Off Axis The difference in windage may be caused by the scope being off axis. The perfect example of off axis, is a side mount on a Win. M94. The scope has to be directly over the bore and the scope adjustment should not be much off from its center setting. As far as shooting low at 50 yds with a 0 at 100, common when the scope is mounted high. IMO. Swampman1, I Sold it- Tranfer was approved on July 28, 2011, Last edited by 243winxb; August 27, 2013 at 08:20 PM. Reason: Answer Swampman Sold M16A1 Carbine

August 29, 2013, 06:00 AM	#11
Jimro Senior Member Join Date: October 18, 2006 Posts: 7,097	If you zero at 100, the bullet is "rising" up until that point with most loads for 223. Combine that with a high scope and it is easily 1" low at 50. Most scopes are set to be parallax free at 100 and beyond, so you have to hold your eye in the same spot every time to make the same shot every time. Jimro __________________ Machine guns are awesome until you have to carry one.

August 29, 2013, 10:27 AM	#15
Brian Pfleuger Moderator Emeritus Join Date: June 25, 2008 Location: Austin, CO Posts: 19,578	Ok, if you've got your scope about 3-3.5 inches above the bore, you could be at 1" low at 50 with a 100 yard zero. Any lower and you're going to have to be at 2,900 fps or less to get 1" low at 50 with a 100 yard zero. At that point, you're "zero" is essentially from 92 to 111 yards, within 0.1", and you'd be zeroed again at 166 yards and within 0.1" from 157 to 175. __________________ Nobody plans to screw up their lives... ...they just don't plan not to. -Andy Stanley

August 27, 2013, 04:40 PM	#2
JimDandy Senior Member Join Date: August 8, 2012 Posts: 2,556	Was the barrel the same temp? Same rest? Were you ON the barrel? Either with the Rest or with your hand/sling etc.?

August 27, 2013, 05:05 PM	#3
higgite Senior Member Join Date: October 21, 2010 Posts: 1,025	Parallax?

August 27, 2013, 05:44 PM	#5
rebs Senior Member Join Date: January 10, 2012 Posts: 3,881	the barrel should have been the same temp since I shot the same number of shots starting with a cold barrel. I use the same rest under the hand guard, no sling.

August 27, 2013, 06:26 PM	#6
Bart B. Senior Member Join Date: February 15, 2009 Posts: 8,927	Try shooting at 100 again then shoot at 50. There's a good chance you're not shouldering and holding the rifle the same at each distance.

August 27, 2013, 07:10 PM	#9
Swampman1 Senior Member Join Date: February 17, 2013 Location: South Louisiana Posts: 432	243, me likes that rifle...wanna trade for my Colt LE6920?

August 29, 2013, 05:52 AM	#10
rebs Senior Member Join Date: January 10, 2012 Posts: 3,881	My scope is mounted a little high as it is on 1/2" risers with see through mounts to get it high enough for a good cheek weld. If I just use the see through mounts without the 1/2" risers then it is hard to get my head low enough on the stock. Its a flat top AR and the scope is about the same height as where the iron sights are with the carry handle on it.

August 29, 2013, 10:13 AM	#13
higgite Senior Member Join Date: October 21, 2010 Posts: 1,025	Jimro is right, a typical AR zeroed at 100 yds for a typical 55gr FMJ load will print about 1" low at 50 yds. So, you have no problem elevation wise. If your rig is truly zeroed for windage, then it's zeroed for all distances. Gravity doesn't work sideways. Disregarding parallax, if it's truly shooting 1" wide at 50 yards, it would be 2" wide at 100 yds. I'm still going with parallax as the cause for your wide POI at 50 yds. What scope are you using? Is it parallax adjustable?

August 29, 2013, 11:16 AM	#16
MJFlores Senior Member Join Date: April 8, 2013 Posts: 539	Bullets dont rise...they're shot upward on an arc sometimes.

August 29, 2013, 03:19 PM	#17
Jim243 Senior Member Join Date: January 5, 2009 Location: Just off Route 66 Posts: 5,067	Reply #3 & #4 gave you the answer. Parallax! You are not looking at the same spot at 100 yards and 50 yards. The distance has changed between your eye and the cross hairs (actually the angle). You will need to get a parallax correcting scope (AO) or a low fixed power one (4x) set at the factory set to 100 yards. Jim __________________ Si vis pacem, para bellum

August 29, 2013, 03:39 PM	#18
rebs Senior Member Join Date: January 10, 2012 Posts: 3,881	My scope is a Leupold 3-9 x 40, there is no parallax adjustment, only the eye piece, elevation and windage. I had read in an article on the internet that by using a spanner wrench you can turn the objective lens to change the parallax adjustment, I never tried it and don't know if it true or not. With my eyes closed I bring the rifle up to my shoulder and open my eyes and the scope is right there, I see the full circle of view. I believe my eye is always the same distance from the eye piece on the scope. Maybe I am wrong and will check when I go to the range tomorrow.

August 29, 2013, 03:55 PM	#19
Jim243 Senior Member Join Date: January 5, 2009 Location: Just off Route 66 Posts: 5,067	When you change the power, you are moving the recital to or from your eye. Not a lot, but you were talking about a 2 MOA distance at 50 yards (1 inch). The distance from your eye is different between 100 yards and 50 yards, so yes the recital is moving in relation to your retina. (your eyeball changes shape) My suggestion is to set your zero at the distance that you will shoot the most, say 50 yards or 75 yards and you should then be within a reasonable zero anywhere between 50 to 150 yards. I would not take a wrench to that scope. Just set your zero to the distance you shoot the most. Jim __________________ Si vis pacem, para bellum Last edited by Jim243; August 29, 2013 at 04:33 PM.

August 29, 2013, 05:37 PM	#21
balderclev Senior Member Join Date: March 20, 2013 Location: Benton, Arkansas Posts: 120	I zero all my centerfire rifles at 200 yds. I first start at 25 yds and set it at 1.5" low followed by 1.5" high at 100 yds. That puts me close to zero at 200 yds. Horizontal or windage is not affected by your scope at different distances. I would suggest that you zero it at 1.5" low at 25 and then shoot at 100 or 200 yds. Anything variance horizontal is either because of lack of zeroing at 25 or a problem with your platform or holding.

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