Tech Topics

Bore-Sighting and Scope- Mount Alignment with Lasers You’ll probably agree that a concentrated beam of light capable of guiding a 500-pound bomb to a tank-size target from upwards of 10,000 feet is more precise than the human eye. If it weren’t, the Norden bombsight would still be operational with the USAF. It follows then that the same beam of light could be used for more precise bore-sighting and aligning a scope base to the bore.

Bore-sighting as you probably know can be defined as aligning the aiming elements with the bore prior to firing a shot. What you may or may not know is that a scope or other sighting system not aligned with the bore can defeat the most fervently performed bore-sighting job. For many years, we used an optical collimator to check out sight/bore alignment, and were able to assure rifle owners they’d be "on paper" at 100 yards.

On the few occasions our assurance failed, we discovered the It’s equipped with a 650mw laser delivering over 8 hours of use on two AAA batteries. reason to be either out-of-alignment receiver holes (drilled by someone outside the factory) or ring and base deficiencies. Since making adjustments in our bore-sighting equipment due to the discovery, we no longer assure being "on the paper." Depending on the known skill of the hunter or competitor, we can guarantee meat on the table and/ or tight target groups.

The additions made to the shop inventory were not cheap, but with increased business due to firearm performance—spelled "accuracy"—the investment has long since been amortized by greater rewards.

The first addition was a Laser Magic II scope-ring and base alignment tool (Stoney Point Products, New Ulm, MN 56073; The second was an SL-100 Mag Laser Bore Sighting System by Site Lite (Concept Development, Fountain Hills, AZ 85268; Both products are also available from Brownells Montezuma, IA 50171; We chose the SL-100 above others because it fits all caliber rifles, pistols, revolvers, .50-caliber muzzleloaders, and includes a 12-gauge/20-gauge shotgun adaptor.

This feature eliminates the need to purchase separate caliber-specific laser devices. Another positive factor is the ability of the Laser Magic II and SL-100 to work as a team to

Figure 1. Figure 2. Figure 3. provide the ultimate precision for scope installation and bore-sighting. Every step in the following, except for live-fire testing, must take place with the shoulder arm mounted level in all directions and secured in a rifle vise. We’ve found the use of a center bubble level to be an excellent and inexpensive assistant in leveling a gun. The Laser Magic II is used prior to mounting the scope, and is designed for either 1-inch or 30mm rings.

It has a built-in 650mw high-intensity laser powered by two AAA batteries (supplied), providing over 8 hours of continuous use. The unit is turned on by tightening its cap to make battery contact. The beam emitted is projected on a nearby wall. There are V-blocks supplied to correct the beam for straightness, and the beam itself has the form of a scope reticle.

When The center bubble level shown with it can be purchased in most hardware stores. the unit has been properly aligned by rotating it, the "reticle" will spin true and look very much like a four-spoke wheel rotating smoothly on its axis. After that, the Laser Magic is placed in the mounted scope rings, and a visual sighting is taken through the chamber to determine ring and base relationship to center bore. Any misalignment can be corrected by using the base windage screws or shimming the base(s) as needed.

At 25 yards, the "wheel" should be in line with your visual sighting through the barrel. At half that distance, the wheel should be 1 inch high of the bore. Then you replace the laser with the scope. Now that it’s known that the scope is mounted center bore, place the target card supplied with the SL-100 at a distance of 25 feet from the muzzle. Besides the target card and a rigid carrying case, the SL-100 arrives with three adapters and 11 O-rings.

Adapter MA1 fits smaller calibers, adapter MA2 is for calibers .308 to .50, and adapter MA3 serves the shotguns. Specific directions for using each adapter and O-ring are included with the SL-100 so most of them will not be included here.

Suffice it to say for the moment that the .22, .308, and 20-gauge rings are never removed from their adapters; that all rings should be lightly greased before being inserted in the muzzle; and that, after bore sighting, the bore should be inspected to insure no rings have been left behind. Locate the top dead center of the barrel with—what else?—atop dead center finder (from Brownells) and insert the correct adapter/O-ring combination into the muzzle. Set the scope at its lowest power.

Line up the arrow on the laser unit with your top dead center mark, and switch on the beam. Adjust the position of the rifle to center the laser on its target card as shown by the dotted circle in Figure 1. The diameter of the circle will normally range in size from 1/2 to 3/4 inch. The firearm must not move, and the laser must stay centered on the target card while any focusing of the scope takes place. Align the scope crosshairs as shown in Figure 1 or Figure 2.

It’s necessary to focus the scope on the laser spot to compensate for the lower velocities and heavier bullets of shotguns and blackpowder long guns respectively. Final scope adjustments must be made during alive-fire session with the first shots taken at no more than 25 yards. Keep in mind that the target card is calibrated for a scope height of 1.5 inches above the barrel (center-to-center of scope-to-bore).

For high-mounted scopes, anew elevation line must be drawn above the dotted line on the card to compensate for the difference. For example, if the scope is 2.5 inches center to center, mark a line 1 inch above the existing dotted line and adjust the scope elevation to match it. Handguns with red-dot scopes or lasers can be bore-sighted by placing the SL-100 laser in the bore, projecting its dot on any object from 25 to 75 feet away, and aligning the gun’s sighting system with the SL-100 dot.

Due to bullet drop, this technique will not work well at ranges over 75 feet.

Finally, there’s one hard and fast rule: Regardless of the bore-sighter used, always insist that your customer makes the final, live-fire adjustments with the first shots taken at a 25-yard range in order to cover such variables as parallax, bullet spin, internal/external ballistics, and personal anatomy.

If You Can’t Dunk-Kit, You Can Poly Dunk-Kit Over 10 years ago, Bill Laughridge, head honcho of the Cylinder & Slide Shop Fremont, NE 68025; and well known to his peers in the Pistolsmiths Guild, developed a cleaner-lubricant called Dunk-Kit. It worked so well in his busy operation he decided to market it. The product eliminates much of the mess involved in cleaning and lubing dirty handguns, and it sold well.

There was only one question in the minds of some users: The stuff worked great on metal, but would it harm polymer-frame guns? Well, if the pistol was intended for military use, the answer was "no," because martial solvents are much harsher than anything contained in Laughridge’s mixture.

Having seen the result of car The only additional supplies required area bore brush and toothbrush. buretor cleaner being sprayed on a plastic trigger housing, we can understand why the question arose. (It melted it into a useless, formless mass.) To relieve any doubts, Laughridge developed another proprietary solution—Poly Dunk-Kit. How’s it used? In the same way its predecessor is used. You take off the grips, open the action, and immerse the gun for 15 minutes.

Take it out of the bucket, use a bore brush in the barrel and an old toothbrush to scrub rails, breech, and cylinder faces. Put the piece back into the bucket long enough to float off what’s been scrubbed loose, and allow any gunk to settle to the bottom of the bucket. Remove the gun, wipe it down with paper towels, and you’re done. No need to lubricate. A light film of oil will be left behind.

If you want cleaner than that, detail strip the gun after the initial dunking, scrub all the parts individually, and return them to the bucket for a few minutes of bathing before drying them off. If you’re concerned you’ll have to fish around to recover a rebound spring, firing pin, or sear from the bottom of the bucket, you can rest easy. Install apiece of 1/4-inch-mesh hardware cloth formed to fit the bucket and raised above its bottom on 1/4-inch-thick metal or wooden spacers.

This accomplishes two things: Whatever sludge floats off after the individual parts scrubbing will not settle back onto the parts and will settle to the bottom of the bucket below the mesh, and all parts will be retained on the mesh. Recovery is a simple matter of removing the mesh from the bucket. No fishing required. Poly Dunk-Kit is available in several sizes up to 55-gallon drums for high-volume operations. For additional information and pricing, contact the Cylinder & Slide Shop.

Durable Shotgun-Gauge Adaptors from Gauge-Mate Gauge-Mate has launched anew line of shotgun gauge adaptors. These adapters can add versatility, convenience, and ease of shooting to your customers’ favorite guns, transforming a single gun into an all-in-one firing powerhouse Available in 11 sizes from 10 to .410 gauge, Gauge- Mate’s gauge-adapter tubes allow then firing of a smaller-gauge shell without impacting performance.

Uses include lessening the loud, intimidating kick of larger gauge shells, making a shotgun more effective for target shooting; for training bird dogs and gun novices; or for teaching gun-safety courses. Skeet and trap shooters may appreciate them as well. These unique adapters feature patent-pending "Extractor-Grip" technology that allows for quick and expedient spent-shell removal. Gauge-Mate’s adapters are manufactured from corrosion-resistant stainless steel rather than less durable aluminum or carbon steel.

As a result, these adapters can handle any size field or target load as well as environmentally-friendly steel shot. Gauge-Mate adapters are afford ably priced, and can be purchased by calling or by visiting

AG Author Pens Holster Book R. K. "Bob" Campbell, a frequent contributor to these pages, has announced the upcoming release of his newest book, Holsters for Combat and Concealment. Campbell is well known in the magazine and police field; has published over 500 articles, columns, and reviews; has served as a peace officer for 23 years; and holds a degree in criminal justice.

His book covers holster geometry, fitting individuals for the correct holster, concealed-carry holsters, police-service holsters, shoulder holsters, crossdraw holsters, ankle holsters, and others. Each type and their proper selection is covered in depth.

We’re pleased to report that Passport holsters and concealment devices, designed by American Gunsmith editor Keith Lawrence, and manufactured by Passport Sports, Inc. (www. passport–holsters.com) are featured prominently in Camp (www. passport–holsters. com) are among those featured in Bob Campbell’s latest book. bell’s book. Advance copies, signed by the author, are available from MHC Tactics and Consulting Spartanburg, SC 29301) for $22 plus $3.95 shipping. Make your check or money order payable to R. K.

Campbell.

D&L Sports CQB Iron Sight For AR-15/M-16 Flat Tops Dave Lauck, another frequent contributor to American Gunsmith, designed this heavy-duty sight set to be, in his words, "as fast as a pistol and as accurate as a carbine." The rear sight allows for three interchangeable center-sighting devices, an open top notch, and an open top notch with night inserts. (The notch sighting devices are designed for use when the rear sight is mounted at the front end of the upper receiver.) The rear sight is also available with an aperture (ghost ring) center-sighting device for mounting at the rear of the upper receiver.

The rear sight is fully adjustable, then lockable with a series of 17 lock screws. This in effect creates an extremely durable and precisely zeroed fixed sight which can withstand the rigors of police, military, and serious competition use. It also creates a sight that is very difficult for unauthorized personnel to tamper with. The sight is triple cross-bolt mounted on Colt-spec A3 flat tops and features protective base material around the center aiming device to ensure field durability.

The front sight designed to compliment this rear sight features the same durability factor. It replaces the fragile front post on AR-15/M-16 rifles that commonly snaps off under hard use. This more durable blade front sight fits standard front sight towers and allows for a night-sight insert to be installed. The design of this sight set allows for pistol-shooting speed in CQB environments, yet maintains the three-point contact and accuracy of the carbine.

Shooters who choose the notchstyle center sighting device and forward-mounted rear-sight position will be able to use optics in conjunction with the D&L Sports sight set. The sights were designed to be mounted and zeroed, then have their settings locked in order to always have dependably zeroed back-up sights on the firearm. There is ample room behind the forward-mounted rear sight to allow the mounting of Aimpoint, Tripower, Acog TA01, and other similar-size optics.

D&L Sports Inc. produces a special ring mount for Aimpoint and Tripow er sights which positions the optics at the perfect height for high-speed sighting and allows use of these iron sights right through the optic tube in the event of electronic failure. The ring mount is rugged, quick to attach and detach, and holds two extra Aimpoint batteries. For more information, call D&L Sports at or visit ■