This is how I first encountered Magneto (by Zeck, plain torso):

Which is similar to how Cockrum drew him (although he draws that loop below the gorget much longer):

Here are some of the ways Kirby drew him:

The first Kirby image is from X-Men #1. That matches JB's version:

Before the What If Magneto made me look more closely at the costume, I had never noticed those diagonal lines before.

Speaking of Charles Xavier...  for someone who trains mutants in a specialized-combat gymnasium, he hasn't quite been able to pull his weight during these recent skirmishes.  Granted, Gladiator having mentioned that he has telepathic shielding may suggest that all of the  Guardsmen are similarly protected (thereby neutralizing the Professor), and alt-Beast may have been provided with some form of shielding as well, seeing as how he and the Professor were face-to-face, well within Xavier's strike zone, yet *seemingly* having suffered no form of counter attack.  Emphasis on the seemingly.

But that is always the trick with Professor X, isn't it.  It's the "Vanisher Connundrum".  You can't have someone with the most powerful mutant brain on earth just roll in and solve the whole thing with a couple of mind blasts and mind wipes, so he has to be checked pretty quickly in order for the story to progress.

This series is the gift that keeps on giving.  But then, what else would we expect from the guy who created Sathanas, the Conclave, and Golgotha.   I'm just hoping that Mr. Byrne could maybe-perhaps work his magic and somehow resurrect Proteus for these pages.

To me, there are two quintessential images of Magneto, one from X-Men #104 by Dave Cockrum and one from X-Men #111 by our host. I judge all others by them.

When that piece in the middle of Magneto's chest is drawn more like a "U" shape, it reminds me of a magnet.

BTW, just an observation, in the above Cockrum image we see between Magneto's legs a "go to" piece of tech Dave used often.