Hi.......new guy here. I have yet to build any type of ML'er, but i figured for my first post, I could actually talk about something I have some experience with. As a custom knifemaker, I avoid using A36 for fittings like the plague!!! The running joke among some of us metal pounders is that A36 means "Any combination of 36 types of recycled junk" One smith I know made a guard out of the stuff and when it etched it, he could see the outline of a machine screw that didn't totally melt down. Spend the extra money and use 1018.