You'll get different answers to this one.....my answer is to never load a "business" mag to full capacity.....reason: if you never load it to full capacity then you never use all of the available spring energy....downloading by one or two relieves a lot of stress and gives you that much more of an "edge" in reliable function.
Some people load to capacity but replace the springs every 12 to 18 months, others have several mags and rotate them out thus delaying the spring fatigue. My suggestion is to have magazines for "business" use and other magazines to use for practice. Download the "business" magazines by 2 or 3 rds (for double stacks, 1 rd for single stacks) and only fire with them once or twice a year (depending on use conditions) then clean and reload them. Do all your practice with the mags dedicated to practice only and you'll be that much more assured that your pistol will not malfunction at the worst possible moment.
Of course, you'll need to test your "defensive" mags to ensure they work with your preferred ammo but after that just use them only for "business". If you only have two magazines and don't want to buy any more, then use one for "business" (in gun) and one for practice and use the practice mag for the spare mag in defensive mode. It's the repeated compressing / decompressing that causes the most energy loss in the spring but if you never load it to full capacity then you'll always have a little energy left when you need it.
Yes, I know they'll hold 15 rds and people say if it holds it then put that many in ..... but just like everything else, the more you use it the quicker it'll wear out and it'd just be my luck that it'd cause a malfuntion at the time I needed it to work the most ! You'll get the warning that the spring is weak by the slide not locking open on an empty mag or feeding problems with ammo that you know has always worked before (good, reputable American made ammo).
As always, YMMV.
Ken
