Mounting a Rifle Scope (or any other optic)

[FPrice]

What procedure do you use to mount a new scope on a rifle to at least get it in the ballpark when sighting it in? My very few attempts have been drastic failures, I seem to be nowhere near the target. Do new optics usually come with the crosshairs or sighting dot in the middle of the adjustment range?

Any hints will be helpful, thanks.

 

[MassMark]

Frosty. In my experience, 'sort of'. I have only mounted Nikon scopes in multiples, so I can't speak for other manufacturers. DSG is too cheap to provide me with proper scope mounting tools and after having my own tools magically disappear, I've developed a few tricks which brings with it some consistency. First, I make sure my mounts are properly mounted - especially when they come pre-installed. Remington is notorious for under torqued scope mounts. Second, I apply gentle forward pressure with my thumb, when tightening down the base ring. I have no torque wrench - no way to measure inch-pounds, so I just have developed a feel for it. Most of the customers I see come in with scope issues have not properly installed their rings, bases, or a combination. Sometimes, if you just 'free-wheel' while you are tightening your rings down, or under/over torque your base, you will be more off than you think. While I have not checked dials scope to scope to see if they are set the same, I am generally in the ballpark before I bore-sight. I'm not sure if you are bore-sighting, but if not - you should. A laser bore sight is about 25-bucks and can save you some aggravation. You can also go old school and from a bench, look down the bore of your barrel and adjust crosshairs to match. If you get frustrated and need some help, feel free to swing by - I seem to get pretty lucky...

 

[Underwhere]

I've learned a few tricks from members on this forum.

1. Turn the turrets on your scope all the way in either direction. Count the clicks. Then center them (by counting). This is a good starting point and to verify that your scope has the adjustability advertised.
2. When mounting your rings push them forward so the front of the ring makes contact with the perpendicular part of the rail. This ensures that if you ever take the optic off you can replace it with more likelihood of putting it back in the same spot.
3. Go buy liquid electrical tape and coat the inside of the scope rings with it. This prevents you from marring the finish on your scope which happens so damn easy for some reason.
4. Get a feeler gauge from an auto shop. Put the gauge between the top of the rail and the bottom of the scope. This ensures that the rail and scope are level with each other. Once you have tightened everything down pull the feeler gauge out and everything should be fine.
5. Depending on your rifle if you can remove the bolt or action you can look down the barrel and do some visual bore sighting to get you somewhere close to on target. I have never used a bore sighter (though convenient) but I've never taken more than 10 rounds to get on paper and within a few inches of my target.


It shouldn't take you long to get on paper. If your first shot isn't on paper, shoot at the berm and see where the shot hits.
Know how far your adjustments will move your shot (1/8 moa, 1/4 moa etc) so you're not blindly adjusting here and there

 

[whatluck]

A torque wrench is the only way to get it right.

 

[LoginName]

Start your initial zero at 25-50 yards. I have yet to buy a scope out of the box that couldn't put a bullet on paper at the range.

 

[RKG]

Here is the approach I use to boresight new installations:

Install the scope and, after assuring it is true in the rings, tighten all screws per spec.

Remove the bolt.

Mount the rifle in a rifle vise that has a view of an object some known distance away.

Center that object in the view through the bore.

Center the cross-hairs of the scope on the same object.

Using an application such as “Point Blank,” determine the bullet drop from boreline (not the drop from sight line) for the round in question at the distance of intended zero (up to 200 yards).

Convert that number (in inches) to MOA.

Adjust the scope (in the “up” direction on the adjustment knobs, which lowers the cross-hairs) for that amount of MOA.

For example, a 168 SMK at 2700 fps will drop approximately 10.85 inches from the bore line at 200 yards.

After chucking the rifle in a vise, I sight through the bore on a window mullion of an adjoining house (using an upstairs window and making sure the lights in the room are turned off, to avoid scaring anyone) and adjust the vise so that the cross of the mullion is centered in the bore.

I now adjust the scope so that the cross-hairs are centered on the same mullion and then adjust them “up” 10 and ¾ MOA.

There is some error in this process, resulting from the parallax between the scope light of sight and the bore line of sight, which in part is a function of the height of the scope line above the muzzle. Up to 200 yards, this error can be ignored and you’ll still be on paper. In fact, you’ll be surprised how close you are to a final zero.

Two observations: the foregoing process is probably better done at a rifle range than the way I do it; and the distance to the object used for bore sighting has to be at least 50 yards away to keep the parallax error negligible. If you do this at the range and use the same distance for bore-sighting as for intended zero, the parallax error goes to (theoretically) absolute zero.

 

[LoginName]

A inch/lbs torque wrench is the only way to get it right.

I keep one in my firearms tool box.

I don't recall what it breaks at... 25-35 inch lbs (or somewhere in there).

 

[Uncle Ogre]

4. Get a feeler gauge from an auto shop. Put the gauge between the top of the rail and the bottom of the scope. This ensures that the rail and scope are level with each other. Once you have tightened everything down pull the feeler gauge out and everything should be fine.

Can you explain this in more detail? It's not making any sense to me.

 

[Uncle Ogre]

.

 

[Underwhere]

Can you explain this in more detail? It's not making any sense to me.

Assume the bottom of the scope is flat and not curved.
Also assume that the scope base is parallel to the reticle inside the tube.

You use the gauge (which is essentially different thickness pieces of metal) and put enough fingers in to close the gap between your mount and the bottom of the scope.

Once you close the gap between the bottom of the scope and the mount then the scope will level it self if it is slightly rotated.
At this point you tighten the scope down (Be aware when you tighten you will squeeze the feeler gauge so it will be tight removing it)

This ensures that your scope is at least level with the mount. So when you make elevation adjustments they go up and down rather than diagonally. (assuming your rifle itself is being shot level)

 

[Uncle Ogre]

Assume the bottom of the scope is flat and not curved.
Also assume that the scope base is parallel to the reticle inside the tube.

You use the gauge (which is essentially different thickness pieces of metal) and put enough fingers in to close the gap between your mount and the bottom of the scope.

Once you close the gap between the bottom of the scope and the mount then the scope will level it self if it is slightly rotated.
At this point you tighten the scope down (Be aware when you tighten you will squeeze the feeler gauge so it will be tight removing it)

This ensures that your scope is at least level with the mount. So when you make elevation adjustments they go up and down rather than diagonally. (assuming your rifle itself is being shot level)

This makes much more sense. In my head, "Bottom of the scope" was the bottom of one of the bells, and "feeler gauge" was one feeler, not a stack, and I just couldn't make it go.

Thanks.

 

[Billsail]

It shouldn't take you long to get on paper. If your first shot isn't on paper, shoot at the berm and see where the shot hits.
Know how far your adjustments will move your shot (1/8 moa, 1/4 moa etc) so you're not blindly adjusting here and there

This is the patently unscientific method that I have used for years. I pick a spot on the berm, such as a small twig, piece of debris, or a small dark spot, anything. It's easy to see where your shots are going, and easy to make adjustments to bring it close enough to be on the paper.

 

[atmay]

I usually find the biggest piece of paper I can find (we happen to have rolls of butcher paper at my range) and staple it up. Having 10sqft of clean, fresh paper is a magical thing for sighting in. I typically staple a real sight-in target (with 1/2" grid) in the center or so, aim for the bull, ballpark the adjustments till I'm hitting the grid, then use the grid to make some real adjustments.