Skip to main content

Two Common Scope-Mounting Mistakes

Two Common Scope-Mounting Mistakes

After almost a whole year's worth of optics columns, I thought it was high time to pen the ubiquitous "how to mount a scope" story, the standard fodder of new optics editors worldwide. But before you dismiss these two pages and move on to reloading or gun plumbing, it is important to note that though similar stories have appeared in a hundred magazines a hundred times before, it is amazing to see just how often scopes are mounted improperly.

https://www.shootingtimes.com/files/2010/09/st_mountingmistakes_200812-a.jpg
Always tighten base and ring screws to the manufacturer's specs. Overtightening can damage the scope body and affect performance.

Instead of suffering through a detailed description of the entire process, this column will touch on the mistakes I saw most often as a clerk behind the gun counter--things I still see on frequent trips to the range--and how to fix them.

Too-Tight Screws

Riflescopes are a critical, if not the most critical, component of the accuracy chain, and one of a rifleman's biggest fears is that this component will rattle loose, sending his bullet to an unintended location.


Quite often, you see guys up on their tiptoes, two hands on a screwdriver, tightening base and ring screws for all their worth. More often than not, the screw suffers a terrible fate and is mangled beyond repair. Stripped or snapped screw heads are a huge hassle, especially to gun-store clerks, and overtightening will likely lead to a damaged scope or mounting system.


This problem can be solved with an instruction manual, torque wrench, the right bit, and thread-locking compound, according to David Turner, president of Talley Manufacturing. Turner grew up in the scope-mounts business and spends plenty of time sorting out user-induced mount malfunctions.

https://www.shootingtimes.com/files/2010/09/st_mountingmistakes_200812-a2.jpg
This scope was marred by overtightening the ring screws.

"On just about all of our bases, the screws only require 20 to 25 inch-pounds of pressure," Turner said. "The rings' screws get even less--we recommend 17 inch-pounds."

Resist the urge to give the screw an extra turn once the torque wrench pops at the appropriate poundage. It is impossible to mash the bases into the receiver, and overtightening only puts excessive strain on the screw.

Thread locker will hold the screw in place. Turner likes blue Locktite 242, but other manufacturers prefer other products. Read the manual to get the recommended amount of torque for the base and ring screws as well as the correct thread-locking compound. Companies spend a lot of time testing their products and put all that valuable information into the seldom-read instruction/installation manual. So read the manual.


There is some debate on applying thread locker to the ring screws. Personally, I think it is unnecessary, but others jump up and down and guarantee strife and destruction if that dollop of blue magic is not placed on the screw. Ignore me and them; follow the recommendations in the installation manual.

Proper bits are another obvious way to prevent screw damage. I have a couple of different sets and prefer replaceable tips. While my ring and base screws are installed with the right amount of torque, I often work on guns with rusted screws or ones tightened by Atlas himself. Over time, the bits wear down, get rounded edges, and sometimes even snap. Keeping a few extra commonly used bits on hand is cheap and handy.

https://www.shootingtimes.com/files/2010/09/st_mountingmistakes_200812-a3.jpg
An alignment kit will save you trouble by pointing out misalignment between the front and rear rings.

Out-Of-Whack Rings


How often have you removed a scope and been able to trace the ring's outline in the scope's finish or found where the ring's corners dug into the scope body? That means the ring screws were overtightened, the rings were out of round, or both. The aforementioned torque wrench will solve the first problem, and a lapping kit will solve the second. I have seen quite a few sets of lapped rings, and quite a few of those were lapped incorrectly. Remember: Less is more.

Lapping is designed to remove just enough material so there is 100-percent contact between the ring and the scope body. Even and complete contact will prevent the scope from moving. The vast majority of time, only some finish needs to be removed to accomplish this. In some rare cases, a little metal needs to come off if the bases are slightly misaligned or the ring tolerances are stacked in opposite directions. A set of ring-alignment tools--two pointed tubes the diameter of the scope body--will reveal any problems. If the tool indicates drastic misalignment, rotate the rings 180 degrees. If things still look bad, it might be time to try a new set of rings and bases or windage-adjustable bases.

To start, simply apply lapping compound to the inside of the rings, set the lapping bar into the pair, and tighten so that it is just possible to move the bar. After a few rotations and passes between the rings, remove the bar and check your work. With the lapping compound cleaned away, the scope should slide between loose rings without binding or grinding. If it still sticks or grinds, apply more compound and make a few more passes. Some kit instructions recommend removing 60 to 80 percent of the rings' interior finish. Removing too much metal will ruin the rings and allow the scope to move under recoil.

If you are concerned about the scope shifting because of magnum recoil or rough handling, use a pencil to make small witness marks ahead of or behind the ring. It is surprising how well a properly lapped set of rings can grab and hold a scope, even under severe recoil.

Canted or improperly focused reticles and the wrong eye relief were other common problems, but they are topics for future columns. Too-tight screws and out-of-whack rings and bases are two problems that, left uncorrected, could cause you grief, possibly ruin a good scope, and maybe even ruin a great hunt.

https://www.shootingtimes.com/files/2010/09/st_mountingmistakes_200812-a4.jpg
Lapping ensures 100-percent contact between the scope body and theinner ring surface, and it prevents the rings from exerting undue pressure on the scope body.

GET THE NEWSLETTER Join the List and Never Miss a Thing.

Recommended Articles

See More Recommendations

Popular Videos

The Glock 21

The Glock 21

Frank and Tony from Gallery of Guns spice up the Glock test using their non-dominant hands.

The Future Of Special Operations Small Arms

The Future Of Special Operations Small Arms

We're taking a look at what the Army's Elite Units are using for service rifles and what the future of SOCOM sniping looks like.

All About .300 Blackout

All About .300 Blackout

The .300 Blackout is here to stay, and we take some time to look at new technology surrounding this cartridge. Next, we pit subsonic rivals against each other before stretching the legs of this CQB round out to 600 yards from a short 9-inch barrel.

Skills Drills: 3-Second Headshot

Skills Drills: 3-Second Headshot

James Tarr runs through the 3-Second Headshot drill.

See More Popular Videos

Trending Articles

Improved bullet ballistic coefficients lead to greater performance and accuracy downrange without upping blast and recoil. Here's why.Improved Ballistics a Key to Accurate Long-Range Shooting How-To

Improved Ballistics a Key to Accurate Long-Range Shooting

Rick Jamison

Improved bullet ballistic coefficients lead to greater performance and accuracy downrange...

With three versions, three barrel lengths, and three different finishes from which to choose, the Savage Renegauge is by definition a eumatic alternative for a variety of shooting situations.Savage Renegauge Shotgun Review Shotguns

Savage Renegauge Shotgun Review

Steve Gash - July 13, 2020

With three versions, three barrel lengths, and three different finishes from which to choose,...

While the 6mm-caliber cartridges that can be considered “great” are few in number, some have long and storied histories.12 Great 6mm Cartridges Ammo

12 Great 6mm Cartridges

Steve Gash - August 20, 2020

While the 6mm-caliber cartridges that can be considered “great” are few in number, some have...

Harvey A. Donaldson may be best known for his .219 Donaldson Wasp wildcat cartridge, but during his lifetime he was popularly called the “pioneer benchrester.”  Harvey Donaldson: Pioneer Benchrester Gunsmithing

Harvey Donaldson: Pioneer Benchrester

Joel J. Hutchcroft - May 07, 2019

Harvey A. Donaldson may be best known for his .219 Donaldson Wasp wildcat cartridge, but...

See More Trending Articles

More Optics

TRUGLO has a new series of red-dot optics designed for close-quarter, fast-sight acquisition scenarios. Two optics are offered: IGNiTE 30mm and IGNiTE Mini.TRUGLO IGNiTE Mini Red Dot Optic Optics

TRUGLO IGNiTE Mini Red Dot Optic

Jake Edmondson - June 10, 2020

TRUGLO has a new series of red-dot optics designed for close-quarter, fast-sight acquisition...

The Nikon Prostaff P5 3-12X 42mm Riflescope have enhanced zoom rings, focusing eyepieces, and turret caps all made from aircraft-grade aluminum.Nikon Prostaff P5 3-12X 42mm Riflescope Review Optics

Nikon Prostaff P5 3-12X 42mm Riflescope Review

Jake Edmondson - November 13, 2019

The Nikon Prostaff P5 3-12X 42mm Riflescope have enhanced zoom rings, focusing eyepieces, and...

Crimson Trace enters the riflescope business with the Crimson Trace CTL-3420 4-20X 50mm.Review: Crimson Trace CTL-3420 4-20X 50mm Optics

Review: Crimson Trace CTL-3420 4-20X 50mm

Joel J. Hutchcroft - April 29, 2019

Crimson Trace enters the riflescope business with the Crimson Trace CTL-3420 4-20X 50mm.

Manufactured in the USA, the EOTech EXPS2 HWS provides extremely fast reticle-on-target acquisition out to 300 meters.EOTech EXPS2 Holographic Weapon Sight Review Optics

EOTech EXPS2 Holographic Weapon Sight Review

Joel J. Hutchcroft - March 16, 2020

Manufactured in the USA, the EOTech EXPS2 HWS provides extremely fast reticle-on-target...

See More Optics

Magazine Cover

GET THE MAGAZINE Subscribe & Save

Digital Now Included!

SUBSCRIBE NOW

Give a Gift   |   Subscriber Services

PREVIEW THIS MONTH'S ISSUE Arrow

Buy Digital Single Issues

Don't miss an issue.
Buy single digital issue for your phone or tablet.

Buy Single Digital Issue on the Shooting Times App

Other Magazines

Special Interest Magazines

See All Special Interest Magazines

GET THE NEWSLETTER Join the List and Never Miss a Thing.

Phone Icon

Get Digital Access.

All Shooting Times subscribers now have digital access to their magazine content. This means you have the option to read your magazine on most popular phones and tablets.

To get started, click the link below to visit mymagnow.com and learn how to access your digital magazine.

Get Digital Access

Not a Subscriber?
Subscribe Now