one manufature I am familiar with that doesn't like reloads is GLOCK. In some ways, GLOCKs are great guns, in others, they are the pits.
When a cartridge is fired, the firing pin pushes the cartridg forward until it is stopped by either the chamber /throat junction, on a rimless case, or the rim on a rimmed case. Sometimes in a revolver chambered for a rimless case, the "moon clip" does the head spacing. When the cartridge fires, the case walls are forced to stick to the chamber walls, and the head of the case slams into the breec face, reseting the primer. The case actually stretches, then springs bac to it's original length as the pressure goes down,and in an auto loader, the action unlocks. It is then pulled from the chamber by the extractor. A couple of things happen here. If the brass is used a lot, the case doesn't spring back to it's original length, particularly with "hot " loads, and must be trimmed occaisionally, or else it will be too long, and cause insufficient headspace. This may causer a semiauto to not return to battery, or not return completely to battery, resulting in a cartridge going off not fully supported by the chamber. A "Kaboom"
Another thing that can happen, even if the case is trimmed correctly, is thinning aof the case above the web, the thick part above the head. There is a radius inside the case for strength, and just above this radius is where most stretchin occurs, because just below the radius, the case is very thick. Given enough firings, brass can get noticably thinner there. Sometimes you can bend a paper clip, and use it to "feel" the thin place. GLOCKs, as well as some other handguns, hve a chamber that does not fully support this very part of the case. Everthing is fine on factory ammo, but after one two, or ten firings, the unsupported case head can fail. "Kaboom".
Another factor is just plain human error. Read"stupidity". I am waiting on a new cylinder for my pre model 29 44 Smith and wesson magnum. I assume, and I really don't know, but i assume that i double charged a case with Unique, a fairly fast burning powder. ( .3 grains is a mild charge for the bullet I was using. 12 is about max. As near as I can tell, I must have cycled the progressive press incompletely, while learning how to use it, and doubled the charge in one cartridge. I notice one shot out of a cylinder full that was terrible in recoil. I thought i had slipped a 310 grain "bear hunting load" in with my target loads. The cylinder was bulged just enough at the end to prevent me from ejecting the case, although the others fell out. That mistake has cost me $140.00 so far, if I only need the cylinder. If I had been using max loads on Unique, I might have lost a hand, or more likely an eye. Undoubtably the cylinder would have burst instead of bulged. I have reloaded all my own ammo for over twenty five years. I only takes one little slip, or one little mistake on new equiptment, and you could be injured very badly, or ruin a barrel, cylinder, slide, frame, etc.
This is one of the primary reasons that i favor a revolver. I don't know anyone who can afford the amount of ammo it takes to get really good at shooting without reloading. It is also a reason, one of many, that i traded off the only GLOCK I ever bought. Don't get me wrong, GLOCKs and other similar handguns are great if you are an occaisonal shooter, but they are not for the real shootist. Course, I they weren't O. K. for you, you would already know all this, and I wouldn't have to tell you.