Skip to main content

How to Mount Scope Rails on a 1911 for Bullseye Competition

How to Mount Scope Rails on a 1911 for Bullseye Competition

NRA Conventional Pistol or bullseye pistol competition was always about shooting iron-sighted pistols and revolvers until a couple decades ago when the NRA changed the rules to allow non-magnified optics. Suddenly, everyone was running red dots on their .22 and centerfire target pistols.

The advantage of a red dot over iron sights for older people like myself with poor eyesight is that we are no longer required to focus on the front sight to shoot good groups. Shooters who would have retired from competition in their '50s are shooting into their '70s. Eyesight is no longer an issue.

Mounting a scope rail to the 1911 slide isn't difficult, but you have to pay careful attention to locating the screw holes. I use the rail from Clark Custom Guns. Machined from aluminum, it is attached with four 6-40 socket head cap screws and provides a clean, low profile installation.

We begin our installation by removing the iron sights from the Springfield Armory slide.  We also want to remove the firing pin and firing pin spring, since we'll be drilling into the firing pin tunnel. Clamp the slide in the mill vise and level it. The rail has a taper, so I set the rail on the slide and level it with a machinist's level.


With an edge finder, we center our spindle directly over the muzzle end of the slide and zero our X and Y axis. Clark does not provide a drawing of the rail showing the distance center to center between the four screw holes so we'll have to measure it.


Attaching a pair of centerline gauges to our digital caliper, we take the necessary measurements. The first hole is .980 inches from the muzzle, so we move our mill table over that distance and spot the hole with a center drill.

Spotting the hole is important, since we are drilling on a curved surface and we don't want the drill to walk off the center line. After spotting the hole, we change to a #33 drill and run it straight down through the slide. Then we install a tap guide in the chuck and tap the hole by hand for 6-40 threads.

Drilling and tapping before we move the table insures everything is in perfect alignment. Now we move the table over 1.775 inches for the second hole and repeat the same procedure. The third hole is 2.350 inches from the second one and deeper. We drill down through the thick part of the slide into the firing pin tunnel and stop.

The fourth and last hole is .900 inches behind the third one. After all four holes are drilled and tapped, check the firing pin tunnel for burrs and clean it up with a chainsaw file as necessary. We don't want burrs inside the tunnel interfering with the firing pin.


Test fit the rail. If everything looks good degrease the tapped holes and the top of the slide. I use Shooter's Choice Quick Scrub III as a general degreaser. The screws should also be degreased, and I keep a glass jar of lacquer thinner on the bench for this purpose. Drop them in the jar and fish them out with a magnet a few minutes later completely degreased.

Now we apply a few drops of Loctite 620 retaining compound to the top of the slide as extra insurance it won't come loose and screw down the rail with the four screws which are each treated with a drop of Loctite 262 threadlocker.

With everything tightened down we let the adhesives set up and mount our Ultradot red dot sight, confident our mounting system is secure. Keep in mind a slide-mounted rail is intended for light target loads (semi-wadcutters), not factory hardball. If you are running full power loads with a scope, a frame mount would be recommended. Also remember you have increased slide mass quite a bit by adding a scope so a reduced power recoil spring will be needed for proper function with light loads.


Springfield Armory 1911

This Springfield Armory 1911 has been modified for NRA bullseye competition with a slide rail and red dot sight. This is a typical configuration for the sport.

The Clark Rail

The Clark rail as purchased from Brownells includes four 6-40 socket head cap screws and an Allen wrench. What it doesn't include is a drawing, so measuring is needed.

Centerline Gauges

These centerline gauges attach directly to the jaws of any caliper and allow easy center-to-center measurement of holes. The cone-shaped points keep them centered in the holes.

Measure Before Drilling

Centerline gauges at work. The holes are 1.4 inches apart. A precise measurement here lets you lay out the holes drilled in the slide for perfect fit of the rail.

Positioning the Drill

Center the spindle over the muzzle end of the slide with an edge finder and zero the X and Y axis.

Driling the First Hole

Then use a center drill to start the first hole .980 inches back from the muzzle.

Drilling

Drill the first hole with a No. 33 drill.

Tapping the Hole

Without changing the setup, tap the hole for 6-40 thread with the aid of a tap guide mounted in the drill chuck.

Apply Loctite

Apply Loctite 620 to the slide under the rail for extra insurance against loosening. Use plenty of thread locker on the screws as well, to prevent loosening as the pistol is fired.

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

Recommended Articles

See More Recommendations

Popular Videos

Transcoded: FANIssue11-SpringfieldEdgeEVAC

Transcoded: FANIssue11-SpringfieldEdgeEVAC

Patrick Sweeney of Firearms News shows off the Springfield Edge AR pistol with a folding arm brace.

Firearms News Reviews the S&W M&P 2.0 9mm Compact Pistol

Firearms News Reviews the S&W M&P 2.0 9mm Compact Pistol

Firearms News editor Vince DeNiro runs the Smith & Wesson M&P 2.0 9mm compact pistol through a self-defense drill.

Pioneer Arms PPS-43C Pistol

Pioneer Arms PPS-43C Pistol

The PPS-43 served Poland and the Russians during WWII. It is now available as a pistol for the US market.

NEMO Arms Omen 3.0 Match Rifle

NEMO Arms Omen 3.0 Match Rifle

Rikk Rambo took the NEMO (New Evolution Military Ordnance) Arms Omen Match 3.0 rifle on a nine-month Alaskan adventure.

See More Popular Videos

Trending Articles

Anarchy Outdoors has introduced a series of upgrades for the T/C Compass and Venture rifles.Anarchy Outdoors Introduces Upgrades For T/C Compass and Venture Rifles Rifles

Anarchy Outdoors Introduces Upgrades For T/C Compass and Venture Rifles

Firearms News Staff - August 22, 2020

Anarchy Outdoors has introduced a series of upgrades for the T/C Compass and Venture rifles.

The Wilson Combat-SIG Sauer WCP320 pistol is now legal for IDPA Stock Service Pistol Class Competition and USPSA Production/Carry Optics Classifications.WCP320 Pistol Now Legal for IDPA and USPSA Handguns

WCP320 Pistol Now Legal for IDPA and USPSA

Firearms News Staff - August 14, 2020

The Wilson Combat-SIG Sauer WCP320 pistol is now legal for IDPA Stock Service Pistol Class...

The Masada is IWI's first striker-fired pistol and is an accurate, good looking polymer handgun that has a great trigger.IWI Masada Pistol Review Handguns

IWI Masada Pistol Review

Bob Taubert - August 19, 2020

The Masada is IWI's first striker-fired pistol and is an accurate, good looking polymer...

For the first time in its 35-year-history, the annual Gun Rights Policy Conference hosted by the Second Amendment Foundation and Citizens Committee for the Right to Keep and Bear Arms will be a virtual online event, due to the current COVID-19 situation.2020 Gun Rights Policy Conference Is Online Event Due to COVID-19 Industry

2020 Gun Rights Policy Conference Is Online Event Due to COVID-19

Second Amendment Foundation - July 16, 2020

For the first time in its 35-year-history, the annual Gun Rights Policy Conference hosted by...

See More Trending Articles

More Handguns

The Taurus TX22 ain't your grandaddy's .22 pistol!Taurus TX22 Review Handguns

Taurus TX22 Review

Paul Scarlata - September 17, 2020

The Taurus TX22 ain't your grandaddy's .22 pistol!

Firearms News tests the powerful .460 Rowland Model, which also shoots .45 ACP! Self defense and hunting for 1911-­Packing Survivalists!Mech-Tech Carbine Upper for 1911 Pistols Handguns

Mech-Tech Carbine Upper for 1911 Pistols

Vincent L. DeNiro - November 30, 2020

Firearms News tests the powerful .460 Rowland Model, which also shoots .45 ACP! Self defense...

Firearms News Editor Vincent DeNiro runs the Smith & Wesson's M&P 2.0 9mm compact pistol through a self-defense drill you can practice, and conducts a quick test of an extended translucent magazine from ETS Group.Firearms News Looks at the S&W M&P 2.0 9mm Compact Pistol Handguns

Firearms News Looks at the S&W M&P 2.0 9mm Compact Pistol

Vincent L. DeNiro - September 22, 2020

Firearms News Editor Vincent DeNiro runs the Smith & Wesson's M&P 2.0 9mm compact pistol...

With the VP9SK-B, Heckler and Koch is giving the American market what it wants and needs.HK VP9SK-B Review Handguns

HK VP9SK-B Review

James Tarr - October 27, 2020

With the VP9SK-B, Heckler and Koch is giving the American market what it wants and needs.

See More Handguns

Magazine Cover

GET THE MAGAZINE Subscribe & Save

Digital Now Included!

SUBSCRIBE NOW

Give a Gift   |   Subscriber Services

PREVIEW OUR CURRENT 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 Firearms News 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 Firearms News 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