Rifle Scopes Please ignore this thread..> I'm an idiot.

[WVshooter]

Sighted in my .308 today.
Shot 2 rounds at 25 yards to verify it was on paper after bore sighting and they impacted .25 low and .25 right.

Moved out to 100 and it went from being .25 right to 3" left.
I haven't sighted in a rifle in years but to me this seems funny. I expected the elevation to change but I figured it would still shoot the same for windage.

I didn't get to shoot beyond 100 yards today so I couldn't check for more deviation down range but does this throw any flags for the more experienced shooters in here?

I only ask because I remember reading posts before about the base screws being crooked from the factory and causing problems.

 

[Topstrap]

Re: Could this be a problem? (or am I paranoid)

After initially getting it on paper and where you think you want it zeroed I do a quick vertical tracking test. I put a tall cardboard target around 75 yards, use a 4ft level and draw a line from top to bottom and then a horizontal line a few inches up from the bottom. Use the level to make sure your vertical and horizontal lines are perfect even if your paper target might be leaning in the stand.

Use that crosshair as your aiming point and shoot a round, you can adjust as necessary for windage but not necessary. Crank the scope one full revolution up and use the same hold as before. Shoot again then turn it another full revolution up and shoot again using the same hold as your first shot. If you have room do it one more time. Then take a straight edge or that 4ft level and see if all your shots are perfectly in line vertically. If they are running at a slight angle then your scope needs turned slightly in the mounts or you're holding the gun crooked and it's not tracking true vertical as you adjust for elevation.

I think there is a few threads on the Hide somewhere that explains more on this but you'll see if that is the reason you're off as you move farther out. When you get it right it'll track right up that line perfectly. The reason I pick 75 to 100 yards is you can get good info at that distance without a lot of natures factors moving your bullet around.

Topstrap

 

[WVshooter]

Re: Could this be a problem? (or am I paranoid)

Thanks for the reply but the tracking in the scope wasn't what I was worried about. After my initial shots at 25 yards to see if it was in fact on paper I made a wrong adjustment on the scope that sent it so high at 100 yards that it was off the paper.

When i dialed it back down about 8 inches it came straight down the line so the vertical tracking seems good.

my concern was that at 25 yards it started out .25 right of center and at 100 yards it was 3" left of center without making any windage adjustment on the scope.
This lead me to fear that my scope may be running at a slight angle left to right as opposed to true with the bore.

 

[Topstrap]

Re: Could this be a problem? (or am I paranoid)

The tracking in the scope is nearly always going to go straight up due to the way it's being moved internally but whether it's tracking straight up compared to your bore and where the bullet is heading is what you're trying to match up. I believe even if your mounting holes are not perfectly aligned with your bore won't cause it to track off like that, it'll just make your reticle be off to one side more inside your scope and you'll lose elevation travel.

It's easier to find that video DEFOOSKING mentioned than to describe what you need to check but from what you described that is something I'd check first since it's so easy and will give instant results.

Topstrap

 

[M40_A1]

Re: Could this be a problem? (or am I paranoid)

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Topstrap</div><div class="ubbcode-body">If they are running at a slight angle then your scope needs turned slightly in the mounts......</div></div>

Once upon a time that's what I used to think too. The fact is that you will not be able to determine by shooting at one single range if the vertical crosshair is aligned with the axis of the bore. It doesn't matter if the scope is straight or turned 30 degrees. If the crosshair is vertical and your adjustments track vertically, you will move the points of impact vertically as well when changing the elevation at one given range, assuming the scope is good.

It would be the same as shooting a rifle with properly aligned scope "home-boy" style (90 degrees on its side) and adjusting the "horizontal" crosshair, which would now be the vertical crosshair, and resulting in a nice vertical string in spite of the whole rig being 90 degrees from vertical.

To determine scope cant in the rings by shooting requires shooting at different ranges. The point of impact changing laterally when switching from one range to another (correctly compensating for wind, of course) is a good indication the scope is not aligned.

 

[WVshooter]

Re: Could this be a problem? (or am I paranoid)

Not likely since it was consistent between a few shots. It went from two shots through one hole at 25 yards a quarter inch right of center to two shots 3 inches left of center at 100 yards.

There's probably no sense in me worrying about it right now. I'll be heading to another range in a couple weeks and have a chance to box test it and take it out in 100 yard increments to well beyond where I'll be able to hit.

I guess I'll know something is wrong if it keeps going further left the further I go past 100 yards.

 

[DWood]

Re: Could this be a problem? (or am I paranoid)

Where is the rest of the story? Were you able to get it zeroed at 100 and keep it zeroed? If so, what is the POI at 25 yards with the 100 yard zero?

 

[Sandbogg]

Re: Could this be a problem? (or am I paranoid)

Sounds perfectly normal to me. If the bullet starts off to the right at 25 it is going to continue to go in the angle / direction it was aimed in increasing increments as the distance inreases. Think of a an angle on a compass, the further away you sight, the bigger the measurment of a degree becomes.
If your elevation was dead on at 25 yards and 1/4 right, I would predict the bullet to impact several inches more to the right and nearly off the paper high at 100 yards.

 

[WVshooter]

Re: Could this be a problem? (or am I paranoid)

I would expect that too. The thing that concerned me is that the bullet crossed the line of the scope from right to left. In other words, the bullet started out to the right of center at 25 yards, and at 100 yards it had crossed the target centerline and impacted 3 inches left.
I would have thought that if the scope and barrel ran true to each other then the bullet would have maintained its .25 right impact or like you said continued off further to the right. It was off the paper high by the way.

It almost seems like my rail would be pointing off to the right. I have a big shooting trip planned in a couple weeks and was worried that it might mean the rifle would shoot further left the further out I place the targets.

I'll try and get to another range tonight and check it at 25 again to see if it's still on center. I'd go to 200 but don't have an outdoor range close by.

 

[M40_A1]

Re: Could this be a problem? (or am I paranoid)

When you moved from 25 yards to 100, did you change any settings on the scope? Elevation, focus, parallax?

 

[sniperaviator]

Re: Could this be a problem? (or am I paranoid)

You need to do a box test. Actually, you probably need to do two or three box tests until you get consistency. Do it at 100 yards.

 

[WVshooter]

Re: Could this be a problem? (or am I paranoid)

I adjusted my parallax for 100 yards.

I'm going to my local indoor range just to shoot it at 25yards and see if it holds center. Most likely I've worried over nothing but I just want to be sure before I pack it up and go shooting out of state.

 

[The_FNG]

Re: Please ignore this thread..> I'm an idiot.

With the new thread title how can i possibly ignore it now?

 

[WVshooter]

Re: Please ignore this thread..> I'm an idiot.

My problems appear to be none.

I shot at 25 yards tonight and split the line in the target about an inch low with three rounds. Put a couple turns up on the turret and split the line, then turned back to zero and put one more through the same hole again.

Paranoia.

 

[oldfatguy]

Re: Please ignore this thread..> I'm an idiot.

How many rounds have you shot sighting in and such? Five round groups will pertty much tell you where your rig is hitting. One or two rounds...not so much.

OFG