So...let me remind you that issues with various firearms will come up, and usually they will be fixed, although sometimes they will not. You may keep hearing about issues with certain guns that are no longer issues with newly manufactured ones, for example.
Next autoloader is going to be a Glock or an XD. Can't afford a USP or another P220-226-229, FNP is unproven compared to the first two (although the design is pretty much ideal I just can't trust it yet) Beretta m9 slide issue and "brittle metal" stories scare me..
First pick the ones that you actually like to hold and handle, and if possible rent them and shoot them to see which ones work best for you (bearing in mind that rental guns sometimes have issues due to neglect). That will answer a lot of questions right off the bat, I think. For example, while I gave serious consideration to the XD, I learned that I didn't like grip safeties in general (really anything that moves when I merely grip the gun). It's a fine gun, and this was perhaps not a deal-breaker, but it was a personal factor that I had not anticipated before trying the gun out.
Regarding the FNP, it's true that it's not proven, and there have been some issues that have come up, so it's still probably in the "teething phase," understandably. I'd only buy it at this point if I really liked it and didn't intend on using it for defensive purposes.
And as for the M9 slide issue, as far as I know that was fixed long ago but keeps coming up regardless. The only major lingering problem with the M9/92FS of which I am aware is a relatively weak locking block that is prone to breakage after a few thousand rounds. People sometimes change them out preemptively like they would springs to avoid unexpected breakages.
Down to a g19, a g21, an XD 45 4"
I prefer the .45, but I include the g19 because I really haven't heard a single bad thing about it.
For what it's worth, the G19 is significantly more susceptible to limp-wristing than just about any modern (or even not so modern) autoloader out there. If you hold it properly, it's one of the most reliable, certainly, and worthy of its legend, but this is its weak point. The G21 is much less likely to fail when limp-wristed for whatever reasons, but it's still more prone than the XD, for example. I don't think this is a huge issue, but for some people it may be.
On the other hand, if you really need a pistol that resists environmental degradation such as corrosion, Glocks are amazingly robust in this regard. XDs had rusting problems early on that have been corrected by now, but I don't think that they or any other pistol can quite match up to Glocks in this regard (Glocks aren't perfect either and can rust, but it's typically extremely hard to get one to).
If you looked up the current definition of a combat/defensive pistol, there'd probably be a picture of the g19 let's face it.
Be careful with this--these are all machines designed by people, and they are all limited by physics, unlike hype. Generally, you trade some things off for others, and while some designs are more optimal than others, there's no need to put any of them on a pedestal.
Haven't heard bad things about it (except people that just hate Glocks period).
Some detractors are envious, while others are tired of the hype, while still others have legitimate gripes and don't see why Glock should be singled out for special consideration. I just go with whatever views and opinions seem the most fair and objective, and suggest that others do the same.
As far as bad things go, besides the limp-wristing issues with all Glocks (albeit some models more than others), their grips don't fit everybody equally well, which applies to every gun basically. Specifically the "hump" bothers some people, while the grip angle is a bigger issue for others, and maybe the texture and cross-section of the grip. It fits many people just fine, too.
Using myself as an example, I would hate the hump on the grip as well as the grip angle if I held it like I would a gun with a shorter trigger reach (inline with my forearm), but since my fingers are slightly short, what happens is that I have to twist my wrist a little, in which case my hand fits perfectly around the hump, which lifts my hand to a nice, high, firm hold, and makes the sharp grip angle work perfectly. Do you see why you have to try these guns out for yourself? I ended up liking the M&P better overall (you might also want to try this one out if you haven't already), but I was still surprised at how very well the Glock fit my hand with a modified hold. However, for some people it's a poor fit no matter what because everybody is different.
I'm kinda favoring the G21 but I've heard a lot of stories about these blowing up....even in departmental testing...
All guns can blow up for various reasons, usually related to ammo. However, I do find it amusing how many Glock aficionados reflexively and immediately blame magazines or ammo if there is even a jam, much less an explosion. No gun is perfect, after all. Watch the 1000-round Glock torture test on YouTube, where every jam was immediately blamed on a bad magazine or bad ammo. That's always a possibility, but then so is the fact that the poor gun was extremely hot (the guide rod actually melted and got ejected, which is not a showstopper) and undoubtedly filthy (could have been limp-wristing, too).
Anyway, regarding the G21, I'm not aware of any major issues with kabooms. Perhaps there was a bad batch of G21s or ammo that caused the issue with some departments. That said, I've always been suspicious of Glocks chambered in .40 S&W (e.g. G22, G23, G27) because of the poor case support of the chamber in stock barrels. Although the issue has undoubtedly become overblown, I think there is a higher incidence of case failures when using .40 S&W Glock barrels made before 2007, which was around when case support was improved. It should be a non-issue with new Glocks, but I for one will not simply dismiss the fact that older Glocks in this caliber left a weak part of cartridge cases unsupported.
from what you know, honestly, with standard 230 gr ball and hollow ammo, is and will the g21 ever be a hand grenade?? Honestly.
Not any more than any other pistol chambered in .45 ACP, to my knowledge.
Because of the lower pressure, would one expect the .45 acp pistols to last even longer than a 9mm? Seems like it'd WAY less prone to malfunction than a 9 or 40...
It depends on a lot of factors, so I couldn't say for sure. I do know that .45 ACP pistols have a long tradition of exploding because of bad ammo, firing out of battery, barrel obstruction, or any of the less common reasons--you name it, it's happened multiple times.
I can only suggest that you only use good ammo, visually inspect each and every cartridge before loading it in a magazine, and stop shooting immediately if you have reason to believe that you just had a squib load.
