Anything made of more parts than an anvil is subject to malfunction and failure! There are so many variables involved in the answer to the question of firearm reliability. But any firearm that has been fired enough to establish that it is functioning properly with good quality ammo can be trusted as much as any can be trusted to give reliable service. Even if I have a perfectly functional firearm, and even if I am firing well known good quality ammo, that ammo can be found to have a round in the box that is not perfectly constructed or loaded. Even a perfectly reliable firearm, if used at all, will eventually require springs or other parts to be replaced to maintain that level of reliability. Every firearm must be maintained and lubricated properly to maintain that reliability. We haven't even talked about the operator induced problems that can result in a problem. All of us are subject at some point or other to limp wristing or failure to take a proper grip to allow the recoil process to have it's best chance to function as intended. I carried revolvers for a great many years as an LEO. I was an instructor each year in the departments academy and was a district rangemaster as well where many thousands of rounds were fired. There were problems. The greatest majority of those were operator induced or caused by sloppy maintenance. Yes, there are examples of any brand that just flat do not work, either from the get go or after some period of time of use. But the great majority function as intended unless they are treated poorly and not well maintained, and IF good quality ammo is used. Even with well known good quality ammo, I maintain the practice of using a simple well made cartridge case gauge to test each round in the box before I load them up in my EDC carry mags or spare round carriers. Even the practice or range ammo that I use is inspected visually and by feel to make sure there are no high primers or buggered cases or improperly seated bullets before use.
If I had a quarter for every time I've known of someone going to the LGS and buying a new or new used firearm and a box of the cheapest ammo on the shelf and retiring immediately to the range, loading up, and attempting to blast away and then complained because the piece of excrement they bought did not function well without problems, then I could buy us all lunch! It is, in fact, surprising how many times this happens and the gun and ammo function reliably! Every firearm will likely function much better after it has been fired a few hundred rounds to allow everything to settle into place and smooth up. I always clean and properly lube my firearms before going to test fire them. I test them for function first. I also always fully load my semi auto mags and lock the slide back on them and put them on the shelf for about 72 hours in that condition before going to the first test firing. That helps the springs to begin to take their initial set before firing and significantly reduces the likelihood of "new gun" related malfunctions. Yes, I've had a very few semi autos that had some problems out of the box, but most could be resolved fairly easily. I've also experienced my own operator induced failures. But I also prepare to deal with common failures to function because it can happen at any time. I only buy known and expected good quality firearms from companies that stand behind their products. I like to buy a good gun for small money as well as anyone, but I also know that a too cheap gun is usually cheap for a reason. I don't let the price point be my criteria for a gun that my life depends on!!! PERIOD!! And I have found that just because I find a particular brand of quality firearm that has real and serious problems means that that brand is not to be trusted across the board. One other thing ... if I find that I'm having problems with most of the brands and models of the same style of firearm, maybe the problem is with me instead of the firearms. All the variables have to be recognized and sorted out to determine what is necessary to rectify the situation.
Most of the negative issues folks have with their blasters are highly and hotly reported and debated. But the very large majority of those who purchase the same guns find they function as reasonably expected, and we don't hear from all of those folks. If I do have problems with a firearm, with every brand of ammo shoot in it, and I really want to keep it, then I attempt to resolve the problems and I don't move it into my carry rotation until it shoots well enough and reliably enough to satisfy my own standards of reliability. A single instance of a problem is not enough to destroy my faith in that firearm, but I shoot it enough to establish that it is not likely to happen again. Certain brands of ammo I will NOT buy again! But any brand can have a problem. Same thing holds true with the brands of firearms. I want my experience with failures to be a VERY SMALL percentage of the rounds I've fired through it. No failures does not mean that at some point in time I won't have one. Stuff happens!! We have to deal with that stuff, and we each have to determine whether we are willing to accept the possibilities for any mechanical object.
Sorry for the long winded post, maybe even a rant, but it seems to me that sometimes our expectations exceed the reality of life. Nothing wrong with wanting things to be as good as they can possibly be, but there ain't nothing perfect in my experience with mechanical things! Thanks for listening.