O.K. The words "width" and "thick" should have sufficed.
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Yes.
Adjust the rests down out of the way (or just temporarily remove them) and you can get at the curve on the top front of the wheels.
It is generally a lot tougher than mild steel at least. Heat and quench and it will be too brittle. And a good screwdriver is not seriously hardened for the same reason. Cheap ones can be either mild steel which will never harden, or carbon steel which may be too hardened and likely to break under serious use. (I've seen both.)
*Seriously* good screwdrivers are likely be forged steel, and ground to final dimensions.But if you heat and quench, you will have something too brittle, and will have to re-heat to draw the temper back to something more reasonable.
Almost nothing is produced full hard -- tools need to be tough as well as hard.
From what I have heard, they are good -- but I have never seen ones which I knew to be Brownells.
But really -- try making something before you spend all that money shipping things across the big pond. You will probably discover that it isn't nearly as difficult as you appear to think it is. And each one you make will be that much easier than the previous one as you gain experience.
Good Luck, DoN.