I agree with you, but I always tell folks to just buy complete extra mags as the tubes can also become damaged, and if you are buying all of the magazine internals and the tubes, you might just as well buy assembled extra magazines. However, I am with you on the need to have spare parts.
Good idea!
Oh I agree, if you have the money, get the mags. I'd like to have 10 or more mags for each gun, particularly the "high cap" mags,4 available for carry, 2 for practice (probably the ones most likely to need the rebuild kit) and 4 sitting in the safe pristine with low humidity and a nice coat of silicone on it to help prevent rust.
The more the merrier, but like I say, depending on budget, one has to prioritize how to most effectively spend limited resources.
I'm going through residency, so I'm very frugal with money, 80-90% of extra money is currently going towards guns, ammo, magazines, parts, accessories (optics, red dots, night sites, lights etc.). There will come a day that I'm satisfied, but I'm a ways away from that... That will be the point that any extra money I spend on 2a related activities will be ammo, range memberships and training... Very little will go towards new guns, something would really have to catch my eye and be a significant upgrade to what is already in the arsenal.
If I knew for a fact that no tyrant would ever try taking firearms away from the people, I'd keep it very simple and probably own 10 or less firearms... But I'm skeptical to say the least.
On a similar note, I'm also very much into physical fitness and I went to the store to buy the Pre-workout I use, HemoRage Black, only to find out it's been verboten by the nanny staters... Sometimes I feel like the guberment wants to ban men, testosterone, hard work & freedom (basically ban me and everything I stand for).
Nutrex Research, Inc. 4/24/12