In my experience, modern polymer pistols are, generally, one of the most reliable tools made by man. Think about the amazing engineering involved: the ability to withstand tens of thousands of rounds of ammunition without a parts breakage.
Still, if you shoot enough, things break. Even Glocks break. In fact, a particular Gen3 Glock 19 I use a lot just broke on me. I have been using this particular gun for about twelve years, and in that time, I have put about forty thousand rounds through it. Recently, the extractor broke. That is the only parts breakage in that timeframe and round count. I have heard of Glocks doing one hundred thousand rounds without a single parts breakage. I am unsure if that is just urban legend, but my most-used Glock did not make it to that amazing number.
The good news is it takes about five minutes to replace the extractor in a Glock or in most modern pistols.
The fact is, all man-made machines break if you use them a lot. The idea that your favorite pistol will not break is a fallacy. Rather than worry about the inevitable, shooters should, instead, turn their attention to the necessary replacement parts and tools to fix their gun when the inevitable happens. Most modern designs are modular in the sense that a simple parts breakage should not require gunsmithing but only some time at home.
This author considers easy parts acquisition a foremost consideration when adopting a primary handgun platform. Personally, I have long used Glock pistols, and the reason for this is aftermarket support, the ubiquity of magazines, and, yes, the availability of spare parts. For this reason, I am inclined towards not only using but recommending the pistol families with the best support available. With this in mind, Glock is still probably the most established, but other widely circulated pistols, such as the Smith and Wesson M&P series and the Sig Sauer P320 and 365 series, are catching up, and many spare parts and aftermarket accessories can be found for these guns as well. Why is this an important consideration?
If your gun breaks, and you have the necessary replacement part on hand, then you can fix the gun in five minutes rather than wait for several weeks while the gun gets shipped to the factory, repaired, and returned. Again, most modern polymer pistols are, quite literally, plug-and-play in terms of parts replacement. Therefore, what parts should you consider keeping on hand?
The Most Common Parts to Break
This does depend on the individual gun model, but generally, the list of parts that is suggested here to keep in stock for your particular pistol platform is fairly common among modern polymer framed, striker-fired pistols.
This one is common, perhaps the most common, part to break. Think about it; that tiny little metal claw does a whole lotta work every time you shoot. If you train hard and practice malfunction clearances and other such manipulations, the extractor likely does far more than just its live fire job. They break, eventually. Fortunately, they are fairly easy to replace on most modern pistols.
Like the extractor, the ejector also takes a beating when shooting, though they tend to break less than do extractors on most guns. These can also be replaced quite easily on modern pistols.
Slide stops, slide blocks, and associated springs
The slide stop, or slide release, lever on the gun can occasionally break, and, more commonly, the spring that powers its ability to hold the slide back on the last round sometimes wears out. Along with the slide stop, the gun may also utilize a slide block that can also give out. Keep spares.
The connector spring is a known issue on Glocks, as they occasionally break. Other modern polymer pistols may be prone to a similar failure.
The Firing Pin
Firing pins can break, and on modern guns, the easiest fix may be the replacement of the entire striker assembly. Keep a spare on hand.
Routine Maintenance Items
Some parts on a gun should be replaced at certain round count intervals, even if the gun is working fine. For most pistols, the main item of concern here is the recoil spring, or the main spring, which is the large spring in the gun that you take out when doing a basic field strip of the weapon. This spring takes the recoil energy, and when it weakens, the recoil can start beating up the frame and slide of the gun. Be sure to replace this spring at the intervals suggested by the manufacturer. Other items may be suggested for replacement at certain round counts, depending on the individual gun.
Maintain a Full Spare Parts Kit
For some guns, you can order an entire parts kit that will have a replacement for every single part in the gun except the main components, which are the frame, slide, and barrel. Typically, the main components don’t fail unless there is a catastrophic disaster due to bad ammo or if something is simply made or tempered incorrectly. If a frame, slide, or barrel fails, then certainly send the gun to the factory to repair or replace it. A spare parts kit, however, will give you spares for all the small internal components that are far more likely to break.
Sometimes, these kits are divided between frame and slide components. I highly suggest the investment if such kits are available for your gun. This way, you have every item in inventory. When something breaks, and you must replace it, just re-order that single piece to re-stock the spare parts kit.
Everything breaks, even the phenomenally reliable pistols we now have. Keep the spare parts necessary on hand to keep your guns up and running.