Canted rifle or canted scope?

[ta406]

So, I just picked up a HighPower Optics RingTrue Alignment Tool and went to work verifying the reiticle alignment on a few of my rifles. The tool is fairly easy to use and I had to make a small correction on a couple of rifles but nothing too drastic.

My dilemma began when I tried verifying the alignment on my 260. Its a Remington 700 action bedded in a new Manners T4A stock. When I use the tool according to the instructions and vertically align the bore/scope, the rifle is canted. By this I mean that looking at the rifle from the butt stock, the rifle is canted to the left. I did not check by how many degrees but it is very noticeable. When I level the rifle from the bolt raceway, the scope is no longer aligned vertically with the bore. Also, when I level the rifle from the raceway, the butt of the stock appears to be leveled vertically.

After I leveled the reticle according to the instructions, I set my anti-cant level. Since I shoot this rifle almost exclusively from the prone position, it is very uncomfortable and unnatural to have to cant the rifle in order to get my reticle level. Either I'm doing something wrong, or there is a misalignment somewhere in my rifle?

 

[bruce_ventura]

Using the Reticle Alignment Tool will align the elevation turret axis to pass through the bore. Using the tool has two steps: 1) plumb the rifle, and 2) plumb the scope. What method did you use to plumb the scope after using the tool to plumb the rifle? You may want to try one of the other methods described in the instructions.

It likely that your scope is offset horizontally from the rifle bore. That would cause the situation you're describing. To be very clear, for long range accuracy you should cant the rifle, not the scope.

If the problem is an uncomfortable shooting position or check weld, the horizontal offset must be pretty large. If you instead level the scope off the receiver, you will have a significant error at long range - I would guess at least 2 clicks of error based on what you're describing.

If that amount of error is unacceptable, you have a dilemma. I recommend that you find out why the scope is offset, and try to fix that problem. Feel free to PM me if you want some guidance.

 

[Dosh]

406, I have seen a few rifles bedded without checking the stock for level. Easiest way to mate the stock and action vertically is a vise and use a level for the stock and your new tool for the action. Some new stocks are quite loose and it is easy to have a bedding job not align with the action.

 

[ta406]

Using the Reticle Alignment Tool will align the elevation turret axis to pass through the bore. Using the tool has two steps: 1) plumb the rifle, and 2) plumb the scope. What method did you use to plumb the scope after using the tool to plumb the rifle? You may want to try one of the other methods described in the instructions.


It likely that your scope is offset horizontally from the rifle bore. That would cause the situation you're describing. To be very clear, for long range accuracy you should cant the rifle, not the scope.

If the problem is an uncomfortable shooting position or check weld, the horizontal offset must be pretty large. If you instead level the scope off the receiver, you will have a significant error at long range - I would guess at least 2 clicks of error based on what you're describing.


If that amount of error is unacceptable, you have a dilemma. I recommend that you find out why the scope is offset, and try to fix that problem. Feel free to PM me if you want some guidance.

When you asked how did I plum the scope. I hung a lead weight off of a rope and used that to align the reticle vertically.

Its nothing that I cant live with, but I have 2 rifles that I shoot prone only. It would be nice to have them both set up the same so jumping from one rifle to the other isnt a huge transition.


I appreciate the help and will probably drop you a PM.

 

[ta406]

406, I have seen a few rifles bedded without checking the stock for level. Easiest way to mate the stock and action vertically is a vise and use a level for the stock and your new tool for the action. Some new stocks are quite loose and it is easy to have a bedding job not align with the action.

That thought also crossed my mind. I was assuming since it was a good quality stock, I wouldn't have any issues. I did wrap a couple of layers of tape around the action screws to keep them centered in the pillars thinking that should prevent any issues before bedding the action.

Thanks for the suggestion.

 

[FearNoWind]

Makes me wonder if your stock wasn't squared when they cut the action relief and barrel channel. Take the action/barrel out of the stock. Level it in a barrel vise and set the scope up normally. Drop it back into the stock.

 

[ta406]

Makes me wonder if your stock wasn't squared when they cut the action relief and barrel channel. Take the action/barrel out of the stock. Level it in a barrel vise and set the scope up normally. Drop it back into the stock.

What method do you recommend to level the action/barrel with? I have a piece of flat bar ground so it sits on top of the bolt raceway and it protrudes out the back of the action a few inches, which is just enough for my level to sit on. Then I level it with a starrett level. Is there a better way?

Thanks

 

[FearNoWind]

What method do you recommend to level the action/barrel with? I have a piece of flat bar ground so it sits on top of the bolt raceway and it protrudes out the back of the action a few inches, which is just enough for my level to sit on. Then I level it with a starrett level. Is there a better way?

Thanks

Wheeler Engineering Level-Level-Level Scope Crosshair Leveling Tool

 

[bruce_ventura]

When you asked how did I plum the scope. I hung a lead weight off of a rope and used that to align the reticle vertically...

You should rule out a reticle misalignment inside the erector tube. Try leveling the scope off the bottom of the turret housing, then check if the reticle is plumb.

I would also put the stock in a vise so that the recoil pad centerline is plumb. Then check the top of the rail or scope mounts with the Reticle Alignment Tool. If the rail is level, then the rifle is mounted in the stock properly and problem is a horizontal offset between the scope and rifle bore.

 

[ta406]

You should rule out a reticle misalignment inside the erector tube. Try leveling the scope off the bottom of the turret housing, then check if the reticle is plumb.

I would also put the stock in a vise so that the recoil pad centerline is plumb. Then check the top of the rail or scope mounts with the Reticle Alignment Tool. If the rail is level, then the rifle is mounted in the stock properly and problem is a horizontal offset between the scope and rifle bore.

This is a new build and also a new scope. It is a Leuopld Mark 4 that was originally a mil dot but I had Leupold change it to their MOA reticle. But I guess that doesn't mean that its not the problem. I will double check that too.

I appreciate all the advice. I will tackle this right after Memorial weekend.

 

[Mikecr]

There is another way to handle this.
Critical is plumb elevation adjustment (either reticle holdover or dialing) as shot. And a natural recoiling rifle hold is also very important. You can have both.

-Pick up a 'ScopLevel': Scoplevel Anti Cant Leveling Device
-Hang your plumb line down range
-Loosen your scope rings
-Comfortably aim your rifle at the plumb line and turn your scope until the crosshair aligns with the plumb line
-Tighten the scope rings
-Now flip up your ScopLevel and lock it down while crosshair is plumb to line (this is now your field level)
-Shoot a plumbline through full elevation adjustment/holdover to validate aimpoint-vs-elevation.

I doubt a Mk4 will have an actual issue here, but that still doesn't mean you'll shoot plumb at this point. Barrels release shots in directions that are dependent on load timing and muzzle position.
So when you change your load, you may be changing your elevation line as shot.

For dialers(like me) in the pic below I show a black plumb line, and a ~40moa shot line in red. Draw through the mean of shot line with a yardstick, and measure top deviation from plumb. Take that measure and use it to draw a mirror image of your shot line on the other side of the plumb line (green line).
Now again with the rifle in comfortable hold, turn your scope to put the crosshair on the green line. Counter this scope turn with adjustment of your 'ScopLevel' so that it's level again with your comfortable hold(and the crosshair along the green line). tighten all down good.
Now when you shoot the plumb line, with dialing, your shots will actually be plumb.

For hold overs you would hold the gun comfortable and turn the scope till the cross hair falls on the green line, and then readjust the 'ScopLevel' for level with your comfortable hold. Now hold overs through full elevation will be right.

 

[ta406]

So, I think I figured out the issue. I ran through all the suggestions that you guys gave me and came to the conclusion that when I place a .010 shim between the right side of the scope rings and the base (picatinny) that it brought everything into alignment. So I basically canted the scope rings into alignment with the bore. While I know this isn't a permanent fix, I at least I know where my problem lies. I don't have a mill, but I'm guessing the proper fix is to mill .010 off the opposite side of the rings. Is there any other solution providing the rings are not out of spec? Possibly weld up, redrill and tap the holes in the reciever by a gunsmith?

 

[bruce_ventura]

Ok, that works. However, the shims are decreasing the contact area between the rings and the base, which is not ideal. I recommend that you put the shims between the receiver and the base, not between the base and the rings. While you're at it, bed the base with JB Weld or equivalent material. That will embed the shims into the base. When you remove the scope, you won't have to deal with the loose shims.

 

[Mikecr]

On my post above I made an error..
Forget a green line,, align cross hair with RED LINE