Do you break in the magazine(s) you use for every day carry?
Or, do you simply load a new magazine and presume you are good to go?
Personally, I shoot a minimum of 100 rounds of practice ammo followed by 2 full magazines of edc ammo in a new magazine before I consider it suitable for edc. The magazine is loaded to full capacity. To date, all the new magazines have passed this protocol.
What say you?
Please notice that this thread is not about the brand or number of magazines used for EDC.
I never thought of it as “breaking in”, but I do verify proper operation of anything new with everything old before taking it on-line — guns, ammo, magazines, holsters, sights, lights, etc.
WRT magazines specifically, I will use cheaper 3rd party mags for practice when available — but stick to OEM for carry. I don’t have a set standard for how much is “proof” of satisfactory performance.
I also try to re-evaluate once in a while. When I shoot up aging carry ammo, I do it from the carry magazine (neither is part of my practice rotation) to check for performance problems. I do most of my practice with EDC gun and holster, so they are always being observed for variation from expectation.
I shoot about 200 rounds, rotating the mags I will carry. Might as well practice reload drills, while getting used to the new piece.
There is also something to be said for replacing springs and followers. A new magazine could simply mean one that has had the internals replaced when worn. I’ve personally never “broken in” a new magazine other than when I was “breaking in” the handgun associated with it.
Inspecting the magazine lips for excessive wear would be the only point of concern. But to be honest, my duty carry Glock 19 Gen4 still has magazines that came with the original weapon that have no issues whatsoever. Sometimes we tinker with solutions in search of a problem.
YMMV, stay safe.
I’ll simply empty my EDC mag when I go to the range, use them for practice (with FMJ) then fill them with new, similar Gold Dots. That way I know the ammo/mag/gun all work together.
I’m with you. The “break in” of magazines I go through has been with new guns and the magazines that came with them and other OEM magazines. My edc gun is a Gen 4 G19.
Way back in the day all of my guns that take a magazines have been well checked out when I bought them and still have the original magazines that carry with them they still fit nice and tight and only Sligh wear on the sides from putting them in and out or the respective magazine bay. After some 40 years of using them they still all work the way the manufacturer designed them to. Also that’s with many kinds of ammo that I have used out the years. Take Care and be Safe.
None of my magazines needed “break-in” period.
Honestly, if you see problem with mag during first use or manufacturer says his mag need “break-in” period, that’s the first sign of staying away from the firearm. 
Especially for EDC.
If it “breaks-in” after 100 rounds… perhaps it will “break-off” after 1000? 
I’m so happy for you!
I’ll function test every magazine I welcome to the fleet, That’s about it.
I fully load my new mags & let them sit for at least a week, after that I run them for a hundred or so rounds. The only problem I have ever had is With single stack 380 mouse guns which I don’t fire often.
I resemble that remark. Definitely test when new and run each magazine through the weapon to clear old ammunition in my EDC and staged weapons.
The only time I have ever had a problem is when I bought a pair of Mil spec mags for my 1911 and they would not lock back the slide. Got them running right but they are hanger queens! Sit in the range bag and loaded with FMJ practice rounds.
Especially true of after market magazines! Most factory magazines work as advertised, but some aftermarket ones will, we’ll, not live up to expectations. In which case you are you are giving life saving advise.