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Aftermarket Adjustable Pistol Sights: What You Need To Know Before Buying

Drawing on years of competitive and recreational shooting with iron sights, we take a look at several products that can upgrade the sighting equipment on your 1911 pistol.

The Bo-Mar rear sight produces
an easy-to-read sight picture. The
Bo-Mar has a wide, flat blade
that measures 0.765 inch wide
by 0.430 inch high and has a
well-defined notch 0.110 inch
wide by 0.100 inch.

Though sights and the way individuals see them is a subjective matter that hinges on visual acuity, age, and the sport in which they will be used, there are certain universal factors to consider when choosing an optimum set of sights. Essentially, the sight enables the shooter to steer the gun and direct the projectile to the target. Sights form the link between your eyes and the target. If a sight is not suitable for a specific target or distance or does not give a picture that can be read easily by the eyes to make necessary corrections, the results will be eyestrain and poor accuracy.

The primary purpose of a pistol sight is to allow the shooter to place his shots on target accurately. In terms of sight picture, the front sight must provide a crisp, rectangular profile under varied lighting conditions and be matched to the notch of the rear sight to give easily visualized light bars on each side. It must also have a clear, flat surface across its top to reference its elevation with the top of the rear sight. Though much experimentation has gone on since the introduction of handgun sights in the mid-16th century, the front sight of choice of serious competitors since the early 20th century has been an elongated vertical rectangle with a flat vertical face known. This design, known as the Patridge, allows close mating and exact visual reference for both windage and elevation when coupled with a suitable rear sight and minimizes glare from ambient light that can alter the perceived sight picture and point of impact. While it is not the best choice for a duty firearm or concealed carry—because it tends to shave leather with its sharp corners when drawn from conventional holsters—the Patridge shape has proven itself consistently on the target range.

The front sight needs to be matched to the rear sight in several ways. It must fill the rear notch, leaving just enough light on each side to allow the eyes to evaluate its equilateral placement in the notch without squinting or straining. Its height must also be compatible with the adjustment latitude of the rear sight; the higher the rear sight above boreline, the higher the front sight must also be. With fixed rear sights, this presents the quandary of allowing an exact sighting for one load only, and the front sight must be carefully filed to the correct height to deliver the projectile to point of aim at a specific distance in a handgun’s arched trajectory. If the distance at which the shooter wants to engage a target changes or different ammunition is used, the sight setting cannot be easily altered and can certainly not be returned to its original setting.

The desire of competitors to shoot different ammunition at a variety of distances has led to the development of aftermarket sights to replace the factory-supplied fixed units. Though adjustable rear sights may vary in size, quality, and configuration, their purpose is still to improve the accuracy and versatility of the handgun.

Another benefit of the aftermarket adjustable rear sights is that they all extend the sight radius by as much as 3/4 inch. Though this extra length may not seem much, the 1911 Colt-type pistol has a factory sight radius of 6 inches. An increase in sight radius of 0.750 inch represents a 12.5 percent longer radius, which can contribute to more precise shot placement. Many tournaments are won or lost by slimmer margins than that.

We purchased and evaluated replacement sight offerings by Millett, Bo-Mar, Mec-Gar, and L.P.A. in terms of durability, reliability, installation requirements and price, ease of sight acquisition, and suitability for specific shooting tasks. Here’s what we found:

Get the Picture
With the exception of the newly developed “ghost ring” sights for pistols, all aftermarket adjustable rear sights come equipped with a square notch to accommodate a rectangular-profile front sight. Since that is the case, it would be easy to assume that you only need to choose the one that is least expensive yet compatible with the front sight and all will be well. But it is not that easy.

Many factory-supplied front sights are short and, that being the case, would be compatible with a rear sight with a relatively shallow notch. While this approach may be quick and easy, it may not provide optimum accuracy.

Here’s why. Visualize two parallel lines. The shorter they are, the more difficult it will be to determine quickly and accurately if they are aligned and of equal width. Conversely, the longer they are, the easier it is for the eye to see any discrepancies in their alignment and size.

Relax your vision, cover the short vertical lines, and look at the taller set of lines. Notice that your eyes can assess their height and width without shifting focus between them. This represents the light bars of the “square” sight picture given by the Bo-Mar sighting system. Now try the same exercise with the shorter lines. Note that your eye wants to move back and forth between the lines to assess their relative length and width. This eye movement causes the eyes to strain and creates the perception that the front sight is swimming in the rear notch on sights that present light bars that are significantly shorter than the notch is wide. This type of picture never seems to settle down and presents problems in stabilizing an accurate sight picture.

From this we can easily see that there is an accuracy benefit to having a sight that provides relatively long light bars. It is generally accepted that they should be approximately as long as the rear notch is wide for best accuracy. In essence, the sight picture should form a square visually. This is especially true for the speed shooting disciplines of I.P.S.C., Steel Challenge, Bianchi Cup, and Second Chance Pin Shoot, where the front sight must be tracked through its recoil arc back into the notch as quickly as possible to allow rapid, accurate repeat shots in as little as 0.2 second.

In the slower paced Bullseye and P.P.C. competitions, long light bars allow better control of the sight picture on target by allowing precise visual input without eyestrain or squinting. The shallower the rear sight notch relative to its height, the more the front sight seems to swim around in it as the eyes and motor functions of the hands try to center the front sight.

Another important parameter is that the front sight must not cover the target. If it does, visual reference becomes impossible. You cannot shoot any more accurately than you can see. If you cannot see an exact visual reference between the sight and the target, accuracy will suffer. This is why many iron-sight bullseye shooters use a 6 o’clock hold. It allows them to reference the well-defined bottom of the circular target with the center of the front sight post, rather than bringing the post to the center of the target where there is no sharply defined reference point.

As distance increases or target size decreases, a smaller front sight and rear sight combination with an appropriately small notch may prove best, provided it has adequate light bars relative to its width and can still be easily seen.

The Bo-Mar: The Standard By Which Others Are Judged
For many years now, most top competitors and builders of top-flight competition pistols for all disciplines specify the Bo-Mar BMCS rear sight on their iron sight guns. There are many reasons for this. Foremost among these is sight picture. The Bo-Mar has a wide, flat blade that measures 0.765 inch wide by 0.430 inch high that tilts slightly to prevent glare from back lighting and has a beautifully well-defined notch 0.110 inch wide by 0.100 inch. When mated to a Patridge front sight that measures between 0.110 inch and 0.125 inch wide, the Bo-Mar gives a precise sight picture with well-defined and easily read light bars. This picture has proven itself to be optimum for most iron-sight shooters under most conditions. In short, of all adjustable sights for conventional pistols, the Bo-Mar has been used to win more tournaments than any other iron sight.

Other attributes that endear it to top competitors are its ability to maintain adjustment under the heavy recoil of full-power .45 ACP pistols, its repeatable click adjustments, and its wafer-thin body measurements of 0.125 inch that allow it to be melted into the top of the slide to give a very tasteful low mount position that blends with the lines of the pistol. A properly installed Bo-Mar looks like it was meant to be there. It has also proven to be durable and able to withstand hundreds of thousands of rounds of full-power recoil without parts failure. In short, it performs. It gives an optimum sight picture, looks good, holds adjustment, and is reliable. Since you simply can’t question years of championship winning results, we will examine our other offerings using the proven Bo-Mar as a baseline for comparison.

The Bo-Mar BMCS is not cheap at $65.95, but quality rarely is, and it will cost you an additional $75 to $90 to have it low mounted, which requires several milling operations and drilling and tapping the slide, but results in a very professional installation. The total cost can be expected to run $140 to $160. In addition, you will need a replacement front sight, but that can be expected with most aftermarket adjustable sights with the exception of the Mec-Gar adjustable rear.

Bo-Mar also offers several rear sights that require no major gunsmithing for Colt Gold Cups, Ruger’s “P” models, and S&W 4506, 4516, 1076, 52, and 9mm pistols.

L.P.A., An Italian Bo-Mar
The L.P.A. sight manufactured in Brescia, Italy, and marketed by Olympic/Safari Arms looked to us like a Bo-Mar BMCS on steroids. It had a blade 0.100 inch wide, a well dimensioned notch measuring 0.120 inch by 0.120 inch, a body 0.075 inch thicker than the Bo-Mar, and a 0.385-inch, 60-degree dovetail base. Overall, the L.P.A. looked very much like a Bo-Mar, and in terms of sight picture, we obtained a sight picture of equal quality.

The L.P.A., however, did have some interesting features not found on the Bo-Mar product. To hold upward tension on the swinging blade, it utilized two separate coil springs located in recesses in the base assembly and swinging arm. Their function is to hold pressure on the arm to prevent it from bouncing, causing premature wear on the hinge pin and to maintain contact between the internal serrations of the adjusting screw and a ball detent to prevent a loss of zero. The Bo-Mar uses one doubled spring to accomplish the same function.

The L.P.A. has two Allen-head set screws in its base to hold it laterally in the slides’ dovetail, whereas the Bo-Mar has a single locking screw. The Italian product also has a set screw on the right side of the base that can be used to lock the rotation of the adjusting screw at a desired setting. While the Bo-Mar has never exhibited any problems, it appears the L.P.A. sight has tried to make a good design perhaps a bit better.

On the down side, the hinge pin of the L.P.A. is a single roll pin, compared to the solid pin used by the Bo-Mar. While the roll pin will not walk with use, we have experienced breakage with other sights where roll pins were used. The L.P.A. unit is still too new on the market for us to remark on the durability of its hinge pin, but there was quite significant mass in the swing arm that may result in shearing under thousands of rounds of recoil. Only extended use will reveal any deficiencies, but Olympic Arms reports no failures thus far.

Installation, like with the Bo-Mar, will require several milling operations to give a professional low mount in the slide. The sight alone, like the Bo-Mar, costs in the neighborhood of $65. The L.P.A. is available with a three-dot sighting system as well as plain black.

Millett Sights: Not The Best Sight Picture We’ve Seen
The adjustable Millett with “target rear” blade has been widely distributed for the last ten years and has even been used as a factory adjustable sight on some handguns. It has one primary advantage over the Bo-Mar in that it fits the original dovetail notch of the 1911 pistol. Installing the Millett requires no gunsmithing except for the addition of a proportionately higher front sight of 0.312 inch to allow it to be zeroed.

The only problem encountered with this arrangement over the years has been that the standard front sight on the 1911 is secured by a small 0.055-inch-wide tenon that is staked into the slide. This worked well with the tiny, low mass, military issue front sight, but when high profile, high mass, Patridge type blades are used, there is a tremendous increase in inertia under recoil. The result is loosened sights and sheared tenons.

Millett’s solution to this problem was to offer front sights that attach by means of two round legs, which are riveted through holes that must be drilled in the slide. This has proven to be a secure arrangement, but has its downside as well. Once the holes are drilled, a Millet dual-crimp front sight is the only one that can be used in those proprietary holes. It costs $150 to obtain the Millett dual-crimp tool to facilitate the job, which would not be cost effective unless you were mounting more than one. In this case we would recommend gunsmith mounting at a cost of $50. Added to the price of the front and rear sight at $16 and $55.60 respectively, the total installation package would be $121.60.

The Millet appeared to be mechanically well engineered with dual tensioning springs, positive click adjustments, and dual locking screws to hold its placement in the slide dovetail. We did have some reservations about this sight, though. The cost of the sight plus installation of the proprietary dual-crimp front sight seemed high for a sight that rides on top of the slide. Aside from that, the sight picture left much to be desired, in our opinion. The notch was 0.130 inch wide and only 0.065 inch deep, giving very short and widely spaced light bars that were difficult to assess quickly. The sight blade appeared to be a casting with rounded edges on its perimeter. Under varying light conditions, it caused a distracting, uneven glare further slowing sight-picture assessment, we thought. Due to these visual shortcomings, we do not recommend this sight for competition.

Millett must be listening to the market, though. The company recently introduced the Marksman Speed/Target blade. It uses the same base unit and has a notch that closely resembles the Bo-Mar design. It is 0.130 inch wide by 0.100 inch deep and gives a vastly superior sight picture to older target blade. We found this blade to give a greatly superior sight picture when compared to the older target blade. If you have a pistol that is already set up for the Millett sights, the Marksman Speed/Target blade will offers a definite upgrade in the sighting equipment.

The downside, however, is that it requires a 0.410-inch-high front sight to match its additional height, and we would highly recommend using the Millett dual crimp or a cross-dovetailed front sight to prevent loosening or tenon breakage under recoil due to the increase in mass of a 0.410-inch-high by 0.125-inch-wide front sight. For reference, this front sight is twice the recommended height of that used with a low-mounted Bo-Mar, and even a 0.200-inch-high front sight attached to the slide by the factory tenon may loosen.

The same type of casting is used for the rear blade of the Marksman Speed/Target blade, and it exhibited the same variable glare off its curved edges that give an uneven reference across the top of the blade under some lighting conditions. The Millett sights are available for most pistols of modern manufacture, and variations such as white outline and three-dot sighting systems are also available.

Mec-Gar: The Economical Choice With Some Interesting Possibilities The Mec-Gar adjustable rear sights are the only ones tested that are compatible with the factory supplied front sights. For the 1911-type pistol they come in two configurations: One for use with the original 0.070-inch-wide military-type sight, and another for use with the larger 0.125-inch-wide front sights on the Colt Series 70, 80, and 90 models.

The Mec-Gar sight was a marvelous feat of engineering, we thought. It had a blade 0.750 inch wide but only 0.250 inch high on the larger model. It fit the original factory dovetail, extended the sight radius by 0.7 inch, and rode low over the slide unobtrusively. Best of all, it used the original factory front sight and was adjustable for elevation and windage. That is certainly a lot of performance in a small package. Also, it sells for $55.60 and requires no gunsmithing or front-sight replacement.

Other features included a single-set screw to anchor it in the dovetail, dual tensioning springs, and clearly marked windage and elevation graduations. The swing arm was secured by two small roll pins. The notches measured 0.120 inches wide by 0.8 inch deep on unit for the modern Colt and 0.08 inch wide by 0.065 inch deep for the unit intended for the Government 1911. While the modern Colt sight did not give optimum sight dimensions, it did provide a sight picture equal to the factory fixed sight. While we would not recommend it for top-level competition, it represented an economical alternative to the factory fixed sight, in our opinion.

On the other hand, the Government 1911 unit had a notch that was dimensioned like a miniature Bo-Mar and, if the rounded front sight was filed to a Patridge configuration, actually gave a half sized Bo-Mar sight picture. Practically speaking, a smaller Bo-Mar sight picture should not be discounted. There are many applications that came to mind. The standard front sight used with normally proportioned rear notches measures 0.125 inch. This subtends 9 inches at 50 yards. If the target is the size of an I.P.S.C. target, 18 inches wide, then there is no problem. However, if you are using a smaller aiming area, such as the 6-inch upper B zone to allow for bullet drop, it becomes difficult to reference center to drop your shots into the A zone. This also applies to Bianchi Cup, the Second Chance Bowling Pin Shoot, and World Speed Shooting Championships. If your front sight covers too much of the target, it becomes difficult to obtain an exact reference, and both accuracy and speed of target acquisition decrease.

In these circumstances, a small but well defined sight picture could be of benefit, despite conventional opinion to the contrary. In fact, I used this miniature Bo-Mar sight picture provided the Mec-Gar rear and a 0.070-inch Patridge front to win the 1991 and 1992 stock gun championship at the World Speed Shooting Championships. I also used it to win the stock class at the 1991 Ernie Hill Desert Classic (I.P.S.C) tournament.

Yes, the eyes must be trained to pick up this miniature sight picture quickly, but it never will block out any target that is reasonably within the capabilities of an iron-sighted pistol.

While this arrangement has definite applications, it must be considered a special-purpose sight. The shooter must have vision accustomed to picking it up quickly and following the tiny front sight during recoil to return it to the rear notch, and his physical techniques must be refined to assist in sight reacquisition. In I.P.S.C., it can be used successfully, especially in tournaments that require some long and difficult shots that challenge the optic sighted Open Class pistols. In steel shooting it gives some leeway in sight placement on target, and if the small post is in that tiny notch, a hit is assured. We do not consider it a sight arrangement for everyone, but for special disciplines, it excels.

However, the Mec-Gar sights are not without problems. The dual tensioning springs sit well forward on the base and thus have little leverage to hold the swinging arm against the adjusting screw under recoil. This allows the screw to gradually unwind and change elevation. The solution is to sight in and then apply blue Loc-Tite 242 to the adjusting screw to hold it in place when not held against the detent in the swing arm during recoil. The other problem we experienced was that the swinging arm and base are hinged by two very small roll pins. In the course of shooting 5,000 to 10,000 rounds of major-power ammunition, we think it is likely the pins will shear.

This has occurred twice on a limited-class I.P.S.C. 1911 in .45 ACP with a known round count, but on my stock Steel Challenge pistol that shoots light .38 Super loads exclusively, the Mec-Gar rear sight has survived 30,000 rounds. The key is to be aware of potential failures and accept the replacement costs and periodic inspection as the price you pay for using the sight for special applications.

The Mec-Gar series of sights is also available for 27 other makes of pistol. They offer the same low profile and are compatible with the factory front sights in three-dot and white-outline variations. For the shooter on a budget whose lifestyle doesn’t call for firing large quantities of full-power ammunition, either model offers a reasonably good sight picture and adjustability at a reasonable cost.

Performance Shooter Recommends
Choosing a replacement adjustable rear sight is a subjective process, but we know from experience that the Bo-Mar-type picture appears to be optimum for most shooters. Many competitors from Bullseye to I.P.S.C. have used the Bo-Mar product with perfect satisfaction for many years, and it has a proven winning track record. While it is the most expensive, especially when tastefully melted into the slide by a skilled machinist, it would be our first choice if we were replacing sights on a 1911-style pistol. The L.P.A. would be a very close second—and it might be our first pick but for the long-established reputation of the Bo-Mar.

The Millett sights provided the least desirable sight picture, in our opinion. The uneven glare coming off the rounded edges of the Millett’s cast rear blade distorts the sight picture under various lighting conditions. Also, it requires a high-cost replacement of the front sight using the company’s dual crimp method of attachment to prevent front sight fly off.

The economical Mec-Gar sights offer great cost savings and some interesting possibilities for experimenting with small size sight pictures for specialized applications. But we think they must be watched for loss of adjustment, and after 5,000 rounds, hinge-pin failure.

When you are buying aftermarket adjustable sights, you get what you pay for. The Bo-Mar and L.P.A. units, although almost four times more expensive once installed than the Mec-Gar units, would be our top choices for an active competition shooter who expects to fire a lot of ammunition downrange. They offer good looks, excellent sight picture, low mounting, and should provide a lifetime of trouble-free service.

Also With This Article
Click here to view "Mounting and Cost."
Click here to view "Relative Dimensions."
Click here to view "Durability & Consistency."
Click here to view the contacts and addresses.

-By Charles Woolley

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