A CERTIFIED ARMORER'S THOUGHTS ON AFTERMARKET PARTS 
The Glock's sustained popularity among both law enforcement and civilian shooters in this country has given rise to a vast array of aftermarket parts, accessories and gunsmithing services, to the point where (arguably) only the 1911 is more "customizable".

That said, most of the aftermarket parts (as opposed to accessories) are sold by guys who make their living selling parts, and are not really necessary or beneficial to the performance of the Glock pistol. Most Certified Glock Armorers - myself included - are not very keen on aftermarket parts, and for good reason. Gaston Glock designed his pistol a certain way for a reason, and it WORKS. Many third-party gizmos on the market not only fail to provide the benefits their sellers claim, but in many cases are unsafe or contribute to premature wear on the pistol. And using these parts will almost certainly void your factory warranty, especially if they should cause some sort of problem with the pistol. My general advice is to stay away from all titanium parts (titanium is hard but very brittle, and not suitable for parts like firing pins) and any parts that replace vital parts of your pistol's operating mechanism (ie aftermarket connectors, trigger bars, firing pins, firing pin safeties, guide rods, etc). There's a lot that can be done to improve a Glock by working with the stock parts and using aftermarket parts in non-critical areas (ie mag springs, sights, etc). This approach will save you money and most importantly will preserve the simplicity and reliability for which Glock pistols are known.

NIGHT SIGHTS 
Having trained extensively in low-light and no-light environments, I am a firm believer in having night sights on defensive firearms, and would certainly not own a carry pistol without them. Many brands and designs of night sights are available for the Glock pistol family, but all use glass elements filled with tritium (a radioactive gas) to provide self-illuminating reference points for aiming in low light. Night sights are available as a factory option from Glock, which until recently used two brands (Meprolight and Trijicon) interchangeably. Recently they have gone to making their own sights and using Meprolight inserts. I have had four different brands of night sights on my various Glocks, and have found the greatest difference to be in the daylight sight picture they provide; at night they all show three green dots. :-) Below are my findings; your experiences may differ.

Meprolight - Currently imported from Israel by Kimber and available for all Glock models. I find the Mepro daytime sight picture to be superior to the other brands; the combination of high profile, narrow rear notch (or is it a wide front blade?) and white plastic inserts make these sights quick and easy to pick up, yet still capable of good accuracy at longer distances. Nighttime sight picture is three crisp green dots with good, even brightness.

Trijicon - The de facto industry standard, Trijicons offer an adequate daylight sight picture and good brightness at night. They have a lower profile and a wider rear notch than Meprolights, so the sight picture is not as clean, IMHO. Also, the white rings around the tritium capsules are white paint, rather than a plastic insert. This means that over time, the white highlights can fade or chip off, degrading daylight performance. Perhaps the biggest strike against Trijicons is their high price - generally $15-20 more than Meprolights.

Trilux - The Trilux name may be little known, but they manufacture OEM night sights for several major brands such as SIG-Sauer. The Trilux night sights for Glocks are similar in shape and design to Trijicons, but appear to be slightly dimmer at night. The Trilux design features a locking setscrew in the rear sight notch. The up-side to this setup is that installation is easy, even without access to an Armorer's sight installation tools. Simply start the rear sight into the dovetail with a mallet and punch, then finger-adjust for windage. Lock down the setscrew when the rear sight is in the desired position. The down-side is that if the rear setscrew should work itself loose, the rear sight will drift out of position, and possibly even out of the dovetail! I highly recommend using a threadlocker on both the front sight screw AND the rear sight screw. Trilux are generally $10-20 cheaper than Meprolights.

IMX/PT - Made by Innovative Weaponry Inc. and sold under the brand names IMX and PT. The "New Glock Style" is a ramped-rear design that extends all the way to the back edge of the slide, and also features the locking screw. The IMX sights offer a sight picture similar to Heine or Bo-Mar competition sights, and the dots are VERY bright at night - brighter than any other brand I've owned. Both IMX and PT offer several patterns of dots, bars or combinations, in several color options. Mine were 3-dot green/green, and that's what I recommend for optimum clarity and brightness. Some of the bar patterns are very fast but highly unconventional, and some of the non-standard colors (red, blue, yellow) are quite dim. NOTE: If your training includes one-handed weapon manipulation that involves catching the gun sights on your belt or holster to perform a slide rack, these sights are NOT a good choice - the ramped rear design will slide off just about anything! This caused me no end of grief in a recent FR&I Level III course, and I promptly replaced the IMX sights on both my G23s with Meprolights upon my return!

TRIGGER ENHANCEMENTS 
The stock Glock trigger is very easy to manage and is conducive to accurate shooting. That said, many shooters transitioning from single-action pistols have difficulty adapting to Glock's Safe Action system. Additionally, the mass-produced stamped metal parts and slightly varying tolerances found in the Glock fire control system can result in a significantly different trigger "feel" from one stock Glock to the next. Fortunately, there are ways to customize or improve a Glock's trigger action simply by reconfiguring or working with the stock parts, rather than replacing them with expensive aftermarket parts that may render the gun unsafe.

The Trigger Bar - the serrated trigger face found on the compact and subcompact Glocks may be replaced with the smooth trigger found in the larger-frame pistols. Some find the smooth trigger to provide a more comfortable, positive contact between the trigger face and trigger finger. Note that the trigger is permanently attached to the trigger bar, so the whole assembly must be replaced. Additionally, the vertical extension of the trigger bar (which bears against the firing pin safety) and the rear "slope" (which bears against the connector) may be lightly polished to remove machining imperfections and generally smooth the trigger pull (see "Trigger Job in a Can" below).

The Trigger Spring - the standard Glock trigger spring is a coil-type unit that, when paired with the standard connector (see below), yields a nominal trigger pull of 5.5 lbs. This spring may be replaced with either the NY1 or the NY2 spring to create a heavier, more consistent (ie revolver-like) trigger pull of 8 or 12 lbs., respectively.

The Connector - this is an angled metal piece against which the trigger bar bears, creating resistance and giving the trigger pull much of its weight. The standard connector is unmarked. There is also a "-" or competition connector which results in a trigger pull of about 3.5 lbs. when used with the standard spring. This is the stock setup in Glock's 17L, 24, 34 and 35 competition pistols, but is generally regarded as too light for duty or self-defense use. Also available is the little-seen "+" connector, which produces a pull of roughly 8 lbs. with the standard spring. This is commonly found in police duty guns, and the feel is similar to that produced by the standard connector paired with the NY1 spring.

Using these three main components in various combinations, it is possible to greatly alter the trigger feel of a Glock pistol without sacrificing any of its safety or reliability properties, or voiding the factory warranty. WARNING! NEVER combine the NY1 or NY2 springs with the "+" connector! The resulting trigger pull may be too heavy to engage, or other reliability problems may arise.

The Carry Trigger - My preferred trigger configuration for a carry Glock is what I call the "carry trigger" (catchy name, huh?). It is really nothing more than a NY1 spring paired with a "-" connector. This combination provides resistance from the beginning, eliminating the initial slack or "dead space" found in the stock Glock trigger pull. This results in a more consistent, DAO-type feel, similar to my Kahrs or a tuned DA revolver. The NY1 spring also gives a more positive trigger reset which allows faster followup shots. Finally, the "-" connector eliminates much of the weight added by the NY1 spring, keeping the pull weight to somewhere near stock (about 3/4lb. heavier, instead of some 3lbs. heavier with the NY1 alone). The only real downside to this arrangement is that the NY1 spring returns the trigger so energetically that it may "slap" the trigger finger a bit, causing finger fatigue or even blistering during extended (several hundred round) shooting sessions.

Reduced-Power Striker Spring - This part from Wolff Gunsprings reduces the force that cocks and releases the striker, lightening both take-up pressure and trigger break pressure by approximately one pound. The resulting pull is much smoother and lighter, but does not come without a cost! Lighter spring pressure means the striker is propelled forward with less velocity, and therefore it may lack sufficient force to detonate harder primers (military surplus, CCI, etc). For this reason, this part is intended for use in competition pistols and is not recommended for duty or carry weapons! If your Glock pistol is used for both defensive and competition purposes, you may want to purchase a separate firing pin assembly with the reduced-power spring installed. That way you can just drop in the "competition" assembly prior to a match, and reinstall the "carry" assembly afterward. If you insist on carrying a defensive weapon with a reduced-power spring installed, do so only after extensive testing with various types of ammunition, and use only ammunition with which the pistol has proven reliable!

The Trigger Job In A Can 
The following was forwarded to me by Glock List member Keith Holmes, and is reproduced here with his permission. I have performed this procedure on several of my Glocks, to good effect.

The Holmesmade Trigger Job in a Can is in no way a new process. It is simply a means of hand lapping the trigger bar to the disconnector and I accept no responsibility for or from you or anyone else for using the directions posted here. If you fuggup your gun listening to a ham fisted hack like me on the Internet, it's your fault. I tacked my name on to it, because I thunk it up on my own, all by my self. This in no way implies that others have not come up with the same fool thing I did, but I put it up on the Glock List before anyone else that I am aware of. So there! :) To perform this operation you will need some Flitz polishing compound (Don't use anything more abrasive that Flitz! You're just smoothing things up a bit, not grinding fancy new shapes into your gun's parts), basic gun cleaning gear and your head screwed on straight. Knowing the proper procedure for detail stripping your Glock is also a good idea. I recommend having fired at least 250 rounds (more is better, here) through the gun before embarking on this adventure. This is to settle everything into place and diagnose any possible glitches in the gun before making any modifications to it.

Now that the standard disclaimers are in place, clear the weapon, chamber and magazine, and put all the ammunition in another room, so the ammo fairy doesn't drop by and leave you a little surprise. Disassemble the gun in proper order and give all the parts in the trigger group a good wipe down, at the least, to remove any oils, greases, crud, gunk or other fouling from the parts. Coat the disconnector and trigger bar with Flitz on all wear points (the shiny spots where the parts rub together), then reassemble up to the point where the trigger block assembly (including trigger spring), trigger/trigger bar assembly, locking block, trigger pin and grip pin are in place. You will not need the slide release right now, but you can go ahead and install the locking block pin, just for grins. T'ain't necessary, though. Now, keep gentle counter pressure on the vertical extension of the trigger bar while you carefully work the trigger bar back and forth. This will feel fairly gritty at first and may jam up, so DON'T force it. Go nice and easy and take your time. After a couple dozen strokes the action will start smoothing up and it will get easier. A few dozen more strokes and everything will feel nice and smooth, almost glass-like. This is the point where you want to stop! Do not continue on from this point or you may cause excessive wear on critical parts of your gun. That's the beauty of doing this by hand. A machine polish can go way too far, way too quickly and will not mate up the surfaces, which is what you have just done.

Disassemble the lower receiver again and give everything the most thorough cleaning you have ever done, including the frame, to remove every last trace of polishing compound from every nook and cranny of all the parts, including springs. This is to prevent bits of compound from getting back into places you don't want them to be and causing you much grief and undue stress later on. The trigger bar and disconnector wear points will have a shiny, mirror like appearance to them and will be near perfectly matched. After cleaning and drying everything, reassemble the gun, lube to spec. and run a basic systems check to verify that nothing bad has happened along the way. Now practice dry firing the gun a few hundred times to familiarize yourself with your new and improved trigger action and head on down to the range for live fire practice to see if you've done any good. :) I use Tetra Gun grease to lube the trigger and disconnector as I find it helps smooth up the action a bit more. It's much better than oil, IMPO. Other greases should work just as well.

So, there you have it, folks! The Holmesmade Trigger Job in a Can! All grammatical and punctuational errors are intended and all responsibility, liability and accountability of any kind are expressly denied, refused, negated, null and voided. Use of the above directions is at your own risk.

The folks at Glockmeister.com have compiled an interesting report on the actual pull weights achieved by various trigger configurations. You may want to consult this as a guide to achieving the results you desire, and remember that lighter isn't necessarily better! I've shot better match scores with my carry-configured G23 than I have with my dot-sighted G17 Unlimited gun with a 3.3lb. pull...

EXTENDED SLIDE STOP

This factory part was introduced by Glock with the G34/35 "Tactical Longslide" pistols, but can be installed in all Glock models except the G36. It features a built-up shelf at the rear which gives better leverage to release the slide from the locked-open position. Note that Glock Inc. and several noted pistol instructors do not recommend using the slide stop lever as a slide release. Instead, they advocate the "overhand" method, where the off hand wraps over the top of the slide and tugs to the rear, causing the slide to return to battery. The factory extended slide stop, however, also makes it easier to lock the slide open for unloading and malfunction clearance, as well as providing an easier option for releasing the slide during one-handed drills. I have this part on all my Glocks (except the G36, which it will not fit without modification) and find it quite convenient.

EXTENDED MAGAZINE CATCH 
Some confusion exists regarding the history of the Glock extended mag catch (mag release). According to Peter Kasler's book Glock: New Wave in Combat Handguns, Glock developed an extended-length magazine catch for the G17/19, which then became the "stock-length" part used in the large-frame G20/21. If this is the case, then why did Glock never produce an extended mag release for the G20/21, as Kasler claimed they had plans to do in the early 90s? The alternate story, which makes more sense to me, is that the "extended" mag catch for the 9/40/357 Glocks is nothing more than the stock-length part from the large-frame pistols, and there never was a dedicated "extended" mag catch developed for either frame size. Whatever the case, the extended mag catch button protrudes about an extra 1/8" from the grip of the pistol. This is not long enough to greatly increase the chances of accidental activation (except perhaps in certain tightly-fitted holsters), but it is enough to make magazine release more positive and easier to accomplish under stress, and makes the button accessible to average-sized hands without needing to break the shooting grip as much. Because of its simplicity, low cost and effectiveness, I recommend the stock Glock part over the two-piece, custom-fitted and metal extended mag releases offered by aftermarket manufacturers.

THE PLUG 
As a side effect of the frame-molding process, Glocks possess a hollow cavity behind the magazine well, which extends the full height of the grip and has a small opening into the action. Dust, dirt, lint and other debris tends to gather here - especially in guns that are carried a lot and rarely cleaned or are stored improperly. In addition to being unsightly, the possibility exists that this accumulated crud may eventually migrate into the working parts of the firearm and cause malfunctions. The simple solution is to seal the entrance to the cavity with a device commonly known as "The Plug". Two basic styles of plugs are offered. The Jentra plug fits flush with the base of the grip, while the Scherer Slug Plug protrudes slightly, doubling as a bevel or ramp to help guide the magazine into the well. The plugs for large-frame, standard and compact glocks all lock into place using the lanyard hole at the bottom of the backstrap. The subcompact Glocks lack the lanyard hole, so the plugs for those models are simply friction-fit into place. I have noticed that newer subcompact Glock frames lack the half-moon cutout at the bottom of the mag well's back wall. The Jentra plug interfaces with this cutout in order to fit flush, and will not work in the newest subcompacts. This is just as well, as in my experience, the friction-fit plugs will work loose over time and with recoil, so I do not use them in my subcompacts anyway. Finally, the Plug not only prevents dust and debris from building up and infecting your Glock, but it also turns an otherwise useless void into a handy storage cavity for small tools, spare parts, or if it's a race gun, extra batteries for an electronic sight.

EXTRA-POWER MAGAZINE SPRINGS 
The weak link in the Glock system is the magazine springs. Because their production is contracted out, the springs tend to be of a quality far below what one would expect from Glock. They tend to "take a set" and become brittle fairly quickly, even if the magazines are infrequently used. This problem seems to be worse with preban magazines than with the "Clinton" 10-rounders. Fortunately, Glock mag springs are inexpensive to replace, so it is a good idea to have replacements on hand for when the inevitable happens. Rather than replacing poor quality springs with more poor quality springs, a better idea would be to install a spring specifically engineered for better performance. The main players in this market are Wolff Gunsprings and ISMI. I have used the products from both companies and they appear to be equally good. An extra-power magazine spring will fix feeding problems related to sluggish, worn-out mag springs, and will have the extra length and strength needed to function properly in preban magazines equipped with extra-capacity floorplates.

STREAMLIGHT M3 TACTICAL LIGHT

The M3 is a lightweight, high-intensity flashlight that clamps onto a Glock's frame rails forward of the trigger guard. Powered by two 3V lithium batteries and producing some 90 lumens of light, the M3 is more powerful than a 3 D-cell conventional flashlight. The light is operated by a rocker switch on the back, which is accessible with either the trigger finger of the shooting hand or the thumb of the off hand. The operator may move the switch in one direction to produce a momentary effect, or move it in the other direction for "constant on." Because the light is mounted on the pistol, the operator can use the same solid two-handed shooting grip as he normally would. Having the light affixed to the gun also leaves the off hand free to perform other critical tasks, such as using a telephone, opening a door, controlling a suspect or fending off a physical attack. The M3 is a useful accessory for a home-defense pistol, but note that mounting even a 3oz. device to a Glock's frame will cause a slight shift in point of aim/point of impact. It is important that the operator train with his home-defense pistol with the light mounted, as well as without, in order to understand and compensate for this variance.

SCHERER "BIG STICK" GLOCK MAGAZINES 
Prior to the 1994 magazine ban, Scherer Supplies produced extra-high-capacity magazines - essentially copies of the magazine Glock designed for the G18 machine pistol - in versions holding 33 rounds of 9mm and 29 rounds of .40 or .357SIG. Scherer magazines are less expensive than factory Glock 18 mags, and for good reason. On the surface, the Scherer mags are closer to Glock factory than any other aftermarket magazine. Like Glock, the Scherer "Big Sticks" have a polymer shell bonded to an inner metal liner on three sides (NFML). The baseplate has the proper locking insert and tabs, and the back of the magazine has witness holes identical to Glock's. Scherer even puts their markings in the same place where the Glock logo would be. But alas, the similarities seem to be only cosmetic; the durability and reliability for which Glock is known simply doesn't carry over to the Scherer product. I used to own several of the "Big Stick" mags. Even when the mags were brand new, they would not load to capacity or feed properly. I replaced the springs with ISMI extra power springs and the followers with Glock followers. That fixed the feeding issues, but after running the mags in my G17 and Mech Tech CCU, the mag lips began to chip and crack at the front where there was no metal liner. This caused more feed malfunctions, so I sent the magazines back to Scherer for repair or replacement. For $5.00 to cover return postage, Scherer replaced all four magazines. I chose one of the bunch and test fired it in my G17, only to have the problem repeat itself. I sent this mag back for replacement, and upon getting a new one back, promptly sold them all. If you absolutely MUST have 30-some rounds on tap for your pistol or carbine, then I recommend you spend the extra money and get factory Glock G18 mags. With the money I got from selling my Scherer mags, I was able to purchase several factory Glock 17rd mags with +3 baseplates. These give me 20 rounds rather than 33, but are of much higher quality and are far more practical.

http://home.comcast.net/~shooter2_indy/glockgear.html

http://www.stevespages.com/pdf/glock_armorers_manual_update.pdf