When is this? After you have your Force 100 spirit or your Force 100 Armor spell you locked on prior to doing anything? Having 25 auto-hits means not worrying the small stuff (like guass rifles). Since it takes, what, a single IP to summon that Force 100 spirit and sic him on someone, I'm pretty sure your armor spell will suck the damage you might take while summoning. Then it's "Say goodnight, Gracie."
Keep the playing field level, Gun Nut, how much karma is this mage at right now, just for Initiation 100 and Magic 100, assume he never learned anything else beyond initiation and magic, and started at Magic 5. Assume he was a member of an Magical Group and performed a Group Ordeal every time he initiated... That's still 35558 Karma. And his body is still at 2, his reaction is still at 2. He only knows the spells he learned as a child.
Who other than an IE or a Great Dragon is going to have karma like that? And from everything I've read, the description you give fits IEs and Great Dragons (heck, IE's probably don't have over 35k in karma). If you can rack up that kind of karma, first of all, I don't care that you can perform these grandiose feats and secondly, your enemies are liable to be as karma loaded, have invented a whole new generation of magic-penetrating bullets specifically built to that mage's specifications.
More over, the Armor spell provides Armor equal to Net Hits (not Force), so no, I'm not trying to get through Armor 100, I'm trying to get through armor of 35. With the right weapons, that's doable. Assuming he learned armor as one of his first spells out of the box.
The problem is, you're looking at the breakdown point of 35k+ karma. Of course stuff isn't going to work. Newtonian physics and the Law of General Relativity both break down for sufficiently large / small objects. So if reality doesn't work in the extremes, I have no problem with game mechanics doing the same. Especially when he has to spend so much edge just to survive the initial spell casting