^ This, *_ALWAYS_*.
In some less-friendly states/areas, this could be a
big problem!
-------
and
^ This is really the long and short of it.
Any serious-use magazine - be it for duty/service, self-defense, competition, or even just serious training/practice (er...a weekend-long class that I choose to not spend time with my family and pay $300+ for? yeah, you bet I'm taking that seriously! and same goes for the range-time I need to carve out of my daily life) - needs to and should always be vetted.
It doesn't matter if the magazine is aftermarket or factory. Yes, aftermarket often presents more concerns, but even with factory magazines, tolerance-stacking is very much still a real-world phenomenon that, although likely rare, is probably going to be at the very least less-than-desirable when it comes to the consequences involved, in a serious-use context.
And don't just bank on brand-name. Virtually *every* make has had issues somewhere in the past: it's like trying to find a car manufacturer that hasn't had a recall.
![Wink ;) ;)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
Yes, even the big-names like Magpul, Lancer, STI, and Springfield Armory have had issues in the past: issues which each manufacturer readily resolved to the satisfaction of their customers, but issues, nonetheless.
Also, it's worth putting in the effort to segregate your vetted serious-use magazines versus your range-beaters. Even those expensive STI and HK magazines are in the end disposable, and only so much retrofitting/repairs can occur. Magazines which are not dependable should be segregated immediately from general use: I like to put them into a "training" pile, particulary if they can reliably cause spontaneous stoppages/malfunctions (and for me, this is a one shot deal: prove to me you're not dependable just one time, and it's into the training pile you go!). In-practice, I will drop magazines just as I would in real-life, but for those times where I check my serious-use magazines for function, I will handle them with more respect, so that I preserve their bodies/components against potential damage.
And towards that final concern, indelibly mark every magazine in an unique manner so that they can be tracked.
View attachment 447
^ That's my #4 practice/training 30-round Lancer L5AWM, sent as a "hostage/proof-of-life" picture by one of my favorite local instructors, when I'd accidentally left it behind at his range after a weekend's worth of learning.
One side is stenciled with a number, the other with my last name. Just a sloppy and quick job because I really don't care much about these mags - remember, they are all expendable.
![Smile :) :)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
There's three on the deck in this pic, plus the one in the gun, and there's two more on my support side, covered by my fat trunk-section in this pic.
View attachment 448
^ Excuse the unloaded yet holstered sidearm - that's a big no-no, I know.
This was at morning zeroing at a beginner-level class (one of the first that I attended!), and we had yet to make-ready our sidearms. [ That's my Daniel Defense M4V5LW, c. 2012, so it's still got that monster pic rail! Look at me, I didn't know enough in this class to even know to pull my stock out farther. We all learn!
]
We know that modern duty/service/defensive-grade firearms are extremely reliable, and that perhaps one of their only weak areas are the box magazines from which they are fed. During troubleshooting of a faulty firearm, being able to isolate the problematic magazine(s) will save you a tremendous amount of time and headache.