For my business I cut out a lot of old boilers and oil tanks...the other day I came across the thickest oil tank I have ever encountered...just under an inch thick..I was cutting a hole in it to fill it with concrete as it was an underground tank not in use any more......I have the tanks cleaned and rendered "Gas Free"; safe for hot work, but I don't like using torches for a few reasons....so I typically use a 41/2 inch Milwaukee angle grinder to make a hole and then continue using a Milwaukee Sawsall...which has worked fine for almost 40 years for me....this tank was just eating the grinding wheels and the blades.....the Super at the complex did not say anything, but disappeared and returned with his reciprocating saw...a HILTI 1250-PE...and some DIABLO carbide blades labeled specifically for THICK METAL....I am not going to say that it cut like butter, but it worked....where my trusty Milwaukee stuff did not ..and it did work well...the DIABLO blades really surprised me how well they cut....I typically use Lenox or Morse blades...the HILTI Saw is quite expensive, but it has muscle...and the blades are priced high also....but they get the job done...I think the blades might have too much of a bite to work in the Milwaukee saw...but if you are going to be doing a lot of heavy metal cutting, and cannot use a torch...this works