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Posted: 1/5/2012 10:36:32 AM EDT
How home you always see pictures of groupings so far from the bullseye.  I mean i get there were five shots the size of a penney, but why not in the center of the target?

Link Posted: 1/5/2012 10:37:56 AM EDT
Alot of times it might be differnt ammo then the gun is currently zero'd for. I know if I'm jsut trying out 10-20 rounds of soemthing I don't bother sighting in, then shooting what's left, just to have to re-sight back to the normal ammo I run.
Link Posted: 1/5/2012 10:38:06 AM EDT
different ammo (projectile weight)
Link Posted: 1/5/2012 10:39:25 AM EDT
Lots of factors.  Rifle can not be zeroed at every distance.  Scope errors.  Wind etc.  You can try to hold on the bullseye, but they don't necessarily end up there.
Link Posted: 1/5/2012 10:40:47 AM EDT
If you are really shooting for groups, you don't necessarily want them right in the bull.  If you start shooting the bullseye out of the target, you loose your repeatable aiming point.
Link Posted: 1/5/2012 10:41:19 AM EDT
When testing loads, you want to see how they group.  You dial in your zero when you find the group/load you like.
Link Posted: 1/5/2012 10:41:45 AM EDT
Accuracy & precision.

Link Posted: 1/5/2012 10:46:33 AM EDT
different ammo (projectile weight)

This.  Different weight and velocity change the POI.  I usually zero for what shoots best and when I shoot other ammo it can be off a little.  With a .22lr at 50 yards the difference may only be an inch, at 100yards it could be 12" between subsonic and high velocity.
Link Posted: 1/5/2012 10:49:17 AM EDT
(The group in your picture is probably due to firing different ammo than normal, but read the rest of this.)

Point of aim and point of impact only cross at two distances, occasionally only one.

For rifles not set up for competition fixed-range shooting, it's better to zero them such that the variation from point of aim is minimized for the furthest distance.

For instance, maybe your options are:

1. Zeroed at 25 yards and 300 yards, but 6 inches high at 100 yards
2. Zeroed at 33 yards and 200 yards, but 3 inches high at 100 yards and 8 inches low at 300 yards
3. Zeroed at 100 yards, but 2 inches low at 33 yards and 18 inches (!) low at 300 yards

Pick one, then take your rifle to the 100-yard range and bang away without adjusting your elevation.  Only in the worst case (3) will your groups be centered.

For small variations like in your pic, different ammo or different positioning of the rifle on a rest can also make the difference.

What makes the jobs of military and police snipers so difficult is that they have to be able to land a single round precisely on target at unknown distances and without a test round.  That means they must be well versed in the ballistic behavior of their rifle and ammo, and must be extremely good at judging distance.

(ETA: Actually, the pic in the OP looks exactly like what a 100-yard zero from a scope or high irons will do at 50 yards without adjustment.)
Link Posted: 1/5/2012 10:50:35 AM EDT

Oh damn that was good.  Thanks.
Link Posted: 1/5/2012 10:53:29 AM EDT
Herman kind I thought.
Link Posted: 1/5/2012 10:55:20 AM EDT
Link Posted: 1/5/2012 10:57:48 AM EDT
I shoot high and left when shooting for groups. If you aim at the center of the target all you will have to aim at is a hole in the target. The cross on the target is much easier to aim at.
Link Posted: 1/5/2012 10:57:49 AM EDT
The tight group is the test of skill and equipment and all that needs to be shown.

Because anybody can click the adjustments to make point of impact match point of aim.  That doesn't take any skill.

But I hear you.  It would be prettier if people would just post the pics of the groups after the sight was zeroed for that ammo.
Link Posted: 1/5/2012 10:59:41 AM EDT


Oh damn that was good.  Thanks.

An excellent illustration.

When shooting for group - to determine if a particular load works well in your rifle, for example, where the group is on the paper is almost inconsequential.

Once you've identified the best load for your rifle, you can adjust the sights so that your point of impact is where you want it - bullseye, or in many cases an inch or two higher than the bullseye at 100 yards so that you've got a nice trajectory that allows you to hold on your target and still hit within a few inches of your point of aim for 300 yards or more.

Unless you're shooting competition you often don't want your group centered on the bullseye.

Link Posted: 1/5/2012 11:06:20 AM EDT
Link Posted: 1/5/2012 11:10:04 AM EDT
A lot of people will be zeroed a bit off of the center so they don't shoot out what they are aiming at. It is hard to be precise when you don't have a precise point to aim at; a bullet hole is not a precise point.
Link Posted: 1/5/2012 11:10:52 AM EDT
Also, your point of impact can change slightly (well within the range of the picture) due to atmospheric conditions (temp, etc.) and how you've got the gun rested.  So instead of adjusting back and forth a little ways everytime and wasting ammo just to get the group over the bullseye again, you just shoot the groups.  

Link Posted: 1/5/2012 11:13:39 AM EDT
It's all relative.  A "minute of bad guy" is good enough.  

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