Scope not lined up with bore

[eelect]

Hi guys

I have scope mounted on one piece mount with level on scope. I have it zeroed at 50 yards but as i move out to 90 yards I'm almost 2 mills off from vertical zero. it does this with ATN scope as well that is a one piece deal too. Is my top rail of my gun off? Is there a remedy for this?

 

[Odoyle]

I'd really worry if it were off horizontal zero.

Since its normal to have vertical zero poi drop the farther the distance you shoot then it's the pellet drop so just hold over. Totally normal...

 

[JimNM]

You must make sure your scope is level to the gun. Otherwise, the further away you are from your zero distance the more the pellet will drift to the left or to the right depending on which way the scope is rotated from plumb. Short of your zero distance, the pallet will be on one side of the vertical and pass the zero distance the Pella will be on the other side of the vertical if your scope is not plumb.

 

[Ripper]

And I’m assuming that your scope is probably mounted pretty high from the bore Which will just magnify the problem that was just mentioned. 

 

[nervoustrig]

Most likely a cant-related problem as mentioned by Jim. There are 2 kinds of cant...scope cant and rifle cant. Please detail how you aligned the scope during installation, and how you oriented the level when you installed it.

The requirements to eliminate cant error are:

1. Align the scope's reticle with the rifle's barrel.
2. Hold the reticle level when shooting.

Item 1 deals with scope cant…i.e. mounting the scope incorrectly.
Item 2 deals with gun cant…i.e. holding the gun incorrectly.

To correctly align the scope to the barrel, set up a mirror at a distance of, say, 5 yards and set your AO to 10 yards. Look through the scope at your reflection in the mirror. Twist the scope in the mounts until the vertical bar of the reticle simultaneously bisects both the muzzle and objective bell. Then lock it down. At this point you have eliminated scope cant (item 1). If it's hard to see your muzzle, add a little dot of White Out or take a dot from a hole punch and tape it to the muzzle with clear tape.

Now to eliminate rifle cant, install and use a level. View a known good plumb line (e.g. hanging string) through the scope and orient the rifle so it precisely aligns to it. Now affix your level so it indicates level. From now on when you're shooting, hold the rifle so it shows level and you can be sure you've eliminated both potential sources of cant error. (Note that a level which attaches to the rail will almost never be correct unless it has a separate fine adjustment, whereas a level that attaches to the scope tube can simply be rotated to the proper position and locked down.)

 

[nervoustrig]

If you are using mildots for your shots fore and aft of 50 yards, scope height has no bearing on cant error.

 

[eelect]

My problem is that it does this with the ATN scope as well. The HD model is like a tank and is one piece. There is nothing to adjust on the ATN. 

I did level everything when mounting the swafa scope. 

 

[eelect]

By the way I meant the poi changes to the right by about 1.5 inches from 50 yards to 90

 

[eelect]

If you are using mildots for your shots fore and aft of 50 yards, scope height has no bearing on cant error.

Yes I'm using mildots for holdover. Not touching the turrets

 

[nervoustrig]

Please detail how you aligned the scope during installation, and how you oriented the level when you installed it. Unfortunately there are more bad tutorials out there than there are good ones so it's altogether common that the source of the error is related to installation of either the scope or the level. 

 

[eelect]

Please detail how you aligned the scope during installation, and how you oriented the level when you installed it. Unfortunately there are more bad tutorials out there than there are good ones so it's altogether common that the source of the error is related to installation of either the scope or the level.

This was mounted couple years ago and never touched it since. I was however suspicious for a long time about my holdovers on longer shots till I watched a video of this happening to another person. A light bulb came on and started digging into it. I can believe the swafa set-up could be mounted wrong but how do you explain the ATN scope doing the same thing?

 

[nervoustrig]

Just going by the odds. It is extraordinarily rare to have a modern gun with the rail and barrel so divergent to cause this problem but it is quite common that either the scope or level (or both) is installed incorrectly.

For example, if your scope installation involved placing a level somewhere on the rifle, it's quite possible to have scope cant (reticle not aligned to the muzzle).

 

[eelect]

Ok. I'll get at it this week and see what I can find. I'll level gun with level then line up reticle with plumb line or door jam

 

[nervoustrig]

Um, please don't level the gun with a level. That only works if everything is mechanically perfect. 

 

[eelect]

Um, please don't level the gun with a level. That only works if everything is mechanically perfect.

So how do I know my gun is perfectly straight not canted to start off with?

 

[nervoustrig]

Either the mirror method described above or with a trusted laser boresight.

 

[eelect]

Ok. That could be my problem. Thanks for your patience

 

[Ripper]

If you are using mildots for your shots fore and aft of 50 yards, scope height has no bearing on cant error.

So you’re saying if I had my scope way Out of plumb,and I Sighted it in at 25 yards and shot at 75 yards there would be no different if the scope was mounted very close to the bore as I could or it was mounted very high?

 

[Ripper]

 Believe it or not I’ve always just eyeballed my crosshairs over the years and never had any problem shooting at long distances. You can say I was lucky and maybe I was but that’s just how it’s been. And I probably have just been lucky because I can say for sure that it can be a problem if the scope is canted.

 

[eelect]