I was working on a Space-y moc today when this happened:

As you can see, the armor cracked clean through on one side of the shoulders, and the other has some nasty-looking stress marks.
This was the result of my putting the armor on a fig, and it got stuck. The helmet came off perfectly fine, but the head would not. So I tried pulling harder, and when that failed, I got a pair of needlenose pliers and pulled the head off. It made an odd crack sound ad the armor went flying off the body. When I finally found the piece it looked like that. I'm kinda bummed because this is currently the only set of SM amor I have, and this is only the second time I've used it. I'm afraid of putting it back on and I'm planning to get some more, the colored kind, in my next order; so does anyone have any advice on how to prevent this happening again?

Either something was wrong with the head or something was wrong with the torso (were they both LEGO?) cause from what i've seen on the SM armor is it takes alot of punishment and I've never, never had a LEGO head that could not be removed from the torso nor needed pliars to do so, was the head glued/painted to the torso?

Both the head and torso were lego, and neither was the head glued or painted.

You were just being too rough with it. The connection of the head to the torso isn't effected by the armor, except for that you can't as readily access the "neck" to grip. If the head was that stuck something else was wrong, or you were just over-eager in getting the fig apart.

My advice in the future would be to just have more patience, and to treat the figures with more care.

I assure you, I have always been more than gentle with my legos, with my BrickForge pieces especially. The armor had always been a bit too small for my legos, I had to put the head in the armor first, and then put the armor on the fig, and that in its own right took a bit of... cajoling, you could say. Putting the armor on first, then trying to put the head on never worked with this.

Always worked for me, in fact I like how it fits right in.

Hmm. Oh well, not much to do about it.

That's very...unusual. I've never heard or experienced of a piece of armor being small for the minifig, and considering they're all made out of identical molds...

This happened to my white SM Armour. Except it was because I was pulling the head/armour off by the armour, rather than pulling the head off first, then removing the armour. I can be very thick at times. xD

Anyrudd, all I'd say is to be more gentle with your LEGO, and never, ever, ever use tools on it.