I can only really speak to striker fire guns, since that is the vast majority of the handguns I shoot.
I have many thousands of rounds through the Glocks and SA XD’s I own and I can’t think of more than a couple malfunctions which include a “kaboom” with commercial remanufactured ammo in a G23 and a G19 that once had a stove pipe that I’ve never been able to duplicate, again with factory reman ammo. I quit buying reman ammo and have not had a malfunction since.
When I was in the military, I qualified on the M9 several times, but only carried them while deployed and only shot a few magazines through those. I had numerous issues during the qualifying session but I’m convinced it was due to the guns being shot so much and the magazine springs being wore out.
In my personal guns, I stick to quality magazines and good ammo, and when I want to run malfunction drills, I simply load snap caps in my magazines and they give me the “smack-rack-fire” drills.
I am NOT saying Glocks or XD’s are flawless. But I’ll say this...during the several Gunsite classes I attended, the plastic striker fire guns in my classes from 2010-2014 (mostly Glocks and some M&P’s and XD’s) all ran pretty much flawlessly, regardless the shooters.
I saw a couple Sigs have problems, and several 1911’s (including some pretty high end guns) that had to be swapped out to finish the class. Was it the guns? I honestly don’t know. I think one older guy shooting a Les Baer finally determined it was his mags causing most issues.
I am NOT knocking Sigs or 1911’s. Wonderful guns! But my cheap little G19’s and G23’s always made it through every class without a cleaning or any additional work.
I was told by one of the seasoned instructors that it wasn’t uncommon to have to have their Smithy look at clients 1911’s. They also sold lots of Chip McCormick 1911 mags to clients whose 1911’s with factory mags would have issues. But he also told me it was rare to see a Glock or an M&P have issues other than shooters failing to seat them properly on loaded mags, especially on tactical reloads. The only other issue was that he’d see clients show up with the Glock mags plus some extra Korean mags, and he said they were hit or miss on reliability. Swapping out to just OEM mags solved any issues the shooters had. That’s why a lot of seasoned Glock guys stick to OEM
Mags and recommend downloading Glock mags by one round. I personally use ETS and Magpul mags these days with great results, but avoid other flavors.
Today, I have friends I shoot with who have PPQ’s, FN 509’s, Ruger Americans, etc. and all say (and I see) the same thing...boring reliability.
Of course, we are talking about center fire guns. Rim fire .22’s can be a bit more finicky and require more cleaning and maybe a break-in period. My G44 was like that for the first few hundred rounds. Now, as long as I clean it every 400 rounds or so and keep it lubed, it’s been pretty much flawless too.
Just my observations and own humble opinion.