What is considered "permanent" or "irreversable" when converting to a ten round mag?

[Rorge Retson]

Sure, I could rid myself of any worry and go for 10 round mags, but I hate the look of those little things. Plus, I'm use to standard size mags.

I could not care less how my AR15 "looks"....it's not made for aesthetic appeal, it's made for function. Plus, why would I want my mags to take up 3 x the amount of space with only 1 x the amount of ammo? Makes absolutely no sense. I'd rather have 3 x ammo.

A 10-round magazine (when all I can use is 10-rounds anyway) makes the rifle much more nimble than a 20- or 30-round "looking" magazine, which could actually get in the way in a life-or-death scenario.

I have a number of these, which are the genuine article, and work excellently (and also happen to be on sale until 10/31):

http://www.midwayusa.com/product/388400/ar-stoner-magazine-ar-15-223-remington-10-round-with-anti-tilt-follower-stainless-steel-black

[DFF]

I do have a few 10 round mags just for a "life-or-death scenario". But for range/tactical class use, 10/30 round mags..

[CSACANNONEER]

... I understand that ten round mags are the only option...

Sorry, you understanding is ONLY correct for semi auto, centerfire, AR rifles (I'm not going into handgun laws here) with magazine locks. It is 100% legal for me to use my 20, 20, 40, 100, etc. round mags in my semi auto, centerfire, AR rifle with NO magazine lock and NO evil features.

Now, to answer your question, there is no definitive answer. I'm going with "permanent" means that I would need to drill, cut, grind or otherwise use power tools to disassemble it.

[Garandimal]

What about Eight-round M1 Garand clips...?

Oh, never mind.

[bohoki]

i dont think many actually converts a large capacity

what they do is assemble a magazine from parts that contain a number of rounds less than 11

i think it would be unwise to convert a rare legally owned large capacity magazine since there is very few opportunities to aquire new ones