Sulpher,
As far as circular saw blades, they're working well for me.  Just shot one into a concrete block, from about 30 feet.  It was on my first arrow.  I hardened and tempered it to straw, so don't know how it would work, straight up.  But it didn't break, or bend, and it went in about 3/8".  Cut it out with a cut-off blade and pnuematic grinder.  There's a pic of it, under 'very first arrow' on the first page of the thread, if you're interested.  I'm a carpenter, so free blades, forever, for me.   

dogleg