A Beginner’s Guide to Scope Mounting

By Mark V. Lonsdale

It’s a source of constant amazement to see how many people turn up at the range with no clue how to zero their scopes or, quite often, they are incorrectly mounted to begin with. More than once I have seen scopes mount 90 degrees counter-clockwise, placing the elevation turret on the left side, and the windage is at 12 o’clock, where the elevation should be. Then there are those that turn up at the range with a new scope but neglected to bring the correct tools to mount it.

So here is a few tips for beginners.

  1. If you have never mounted a scope, ask a knowledgeable friend for help, or have the local gun shop do it.
  2. Purchase scopes of known good quality that have a good warranty program. Some companies offer a lifetime warranty on defects but obviously not abuse. You drop it on the concrete, that’s on you.
  3. Invest in good quality rings of the correct size and height – 1”, 30mm, 34mm, 35mm; low, medium, high, extra-high. The goal is to have the scope as low as possible without touching the barrel.
  4. Invest in a good base rail that is matched to your action/receiver. I have a preference for Badger Ordnance 20 MOA rails but there are several quality manufacturers.
  5. Make sure you have the correct tools, wrenches, Allens, or Torx for your rail and rings. Often times the smaller Allens or T15 Torx will come with the scope, but it’s also recommended to invest in a torque wrench. The manual for the scope or installation instructions that come with the rings and rails will give you the correct in-lbs torque values.

Currently, there is no shortage of gadgets out there to aid in mounting and squaring a scope, but I’m old school and have found that the human eye is a pretty accurate alignment tool.

Step 1 – Make sure you have all the right gear and tools

Step 2 – Check and double check that the rifle is unloaded. Remove the bolt. More than one individual has had a negligent discharge in the house prior to cleaning or working on a firearm.

Step 3 – Set the rifle in a secure cradle on the work bench to mount the rail. Set the rail in place to ensure the bottom contours of the rail match the contour of the top of the action. A Remington 700, for example, is rounder in the front and flatter in the rear. Snug the mounting screws down (4) and then insert the bolt to make sure the screws are not so long that they protrude down into the action and interfere with the bolt cycling. If everything is good, then take the screws out, add a small dab of blue Loctite (not red) and then torque the screws to factory specifications (15 in-lbs for Badger with a T15 Torx wrench)

NF Lima51

Rings mounted on the Badger rail so that they don’t conflict with the power adjustment ring on this NF 7-35×56 F1 ATACR

Step 4 – Set the rings on rail as far apart as the rail will allow to begin with. Tighten the cross-bolts finger tight and then remove the top half-shells from the rings. At this point I set the scope in the lower ring-halves to see if it looks approximately right for eye relief and that the scope rings are not conflicting with the elevation/windage turrets, a battery receptacle for an illuminated reticle, or the power adjustment ring. At this point, loosen and move the ring halves to best accommodate the scope but still as far apart as practicable. Then get behind the rifle to check that the eye relief (3”-4” approx.) is correct. This can vary depending on the model of scope.

20170930_142607_resized

NF 7-35×56 ATACR scope correctly mounted with the rings spaced as wide as practicable and correct eye-relief confirmed. I routinely do initial zeroing from the bench, but I set eye-relief for prone shooting since most competition F-TR and ELR shooting is from the prone position. 

Step 5 – Once you have the scope in the right position, add the top cap halves of the scope rings. Add the four screws on each cap ring but keep them loose at this point. Now rotate the scope so that the elevation turret is vertical and windage horizontal. Some shooters use a small float-bubble level on the rail and top turret to ensure they are both horizontal, but I have found that just eye-balling it I can get it right. As I said, the eye is a very accurate tool, especially for carpenters and engineers who can eye-ball even the slightest deviation in horizontal or vertical plains.

Step 6 – Tighten the cap screws just enough to hold the scope from moving or rotating. Then get back behind the rifle to see if the rifle is still vertical in the cradle and if the scope looks to be square on top of the rifle. I am looking at the top of the elevation turret and the side of the windage turret to see if they are horizontal and vertical respectively. I will then get my shoulder into the stock and look through the scope (at the lowest power) to see if the reticle appears to be vertical. It also helps to have a vertical line on the wall to look at, but you can also use a door post provided you have put a level on it and know it is truly vertical.

Step 7 – If everything looks good I will incrementally snug up on the ring half screws and the ring to rail cross-bolts. The goal is to allowing everything to find its natural lay on the scope and in the rail. This is done in increments until I have everything snug. Then torque the cross-bolts to the required 65 in-lbs and the ring screws to 15-18 in-lbs for Badger steel or alloy rings.

Torque Wrenches2

The top torque wrench has the T15 Torx bit for rail screws and cap screws. The T-handle torque wrench is preset to 65 in-lbs for the cross-bolts

Note: If you are using the Nightforce XTRM Ultralite rings CNC machined from 7075-T6 aluminum and titanium crossbolts and jaws, then the crossbolt recommendation is 68 in-lbs., and cap screws 25 in-lbs. For Mark 4 bases, Leupold recommends 22 in-lbs for 6-48 screws and 28 in-lbs for 8-40 screws; and 65 in-lbs for the crossbolts.

AT THE RANGE

You are now ready to head to the range. Starting with a target at 25 or 50 yards, and after setting up on the bench, take a look through the scope and see if everything looks good. One aid that is useful is a vertical line on the target that has been plumbed or leveled to ensure that it is perfectly vertical. This gives you a reference line to compare the vertical line of the reticle.

20170930_143519_resized

The black vertical line down the left side of the target is plumbed vertical as a reference for the reticle

If all looks good, proceed with bore-sighting and then zeroing the scope. More on that in another article. But one step that I have added recently is the use Dead Level tool. This is made by Badger Ordnance and works as an engineered level test bench.

Badger-Dead-Level

Badger Ordnance Dead Level prior to mounting the NF 5-25×56 ATACR. Note the float bubble in the upper left corner of the Dead Level

The way this works is you take the scope off the rifle and attach it to the rail on the Dead Level. Then level the Dead Level to the bench through the use of the float bubble and two adjustment screws that also function as legs. Next, line the scope up with the target that has the plumbed vertical line and see how close the reticle squares to the line. It should be perfectly parallel and, from personal experience, it is a good confirmation that the scope is correctly mounted.

20170819_081034_resized

Looking through the scope, on the Dead Level, at the plumbed vertical black line in the middle of this target

Since you know that the Dead Level is level, and you know that the vertical line on the target is perfectly vertical, then it is just a matter of ensuring the scope is perfectly vertical. If there is any error, loosen the cap screws, rotate the scope and then retighten the cap screws. If everything looks good, torque the cap screws.

The final step is to remount the scope on the rifle, tighten and torque the cross-bolts, and proceed with zeroing the scope.

Final zero with the NF 5-25×56 (left) and the NF 7-35×56 (right)

Lastly, mounting the scope on the work bench takes about 30-40 minutes; and then final adjustments and testing at the range takes about an hour. The important thing is to not rush the process, take your time, follow the manufacturer’s instructions, and don’t over torque or strip and screws.

NF 7-35x56 Lima51

Nightforce 7-35×56 ATACR mounted, zeroed and ready to go to work. 

END

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About Mark V

Dedicated shooter, seeker, traveler, teacher, trainer, educator
This entry was posted in Mark Lonsdale, Rifle Shooting and tagged , , , , , , , , . Bookmark the permalink.

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