Any machining to speak of on the part? If so you might not want to recommend A36 HR because your salesman was telling the truth when he said it might have most anything in it. I recently switched from 5/8 HR to 1/2 CF flat on a device I make and sell. Got tired of having the ends ripped off drills and cutters at random due to hard chunks of who knows what embedded in the HR.

I pay about 50% premium per pound for the CF, but the higher yield allowed me to drop the thickness to 1/2 and still have higher strength than before. Overall material cost about 30% more before I account for lost blanks due to bad material and wrecked tools due to the same. Once everything is considered, I make substantially more per hour on the parts and the aggravation factor is way less.

When you buzz the teeth off a near new $45 bimetal bandsaw blade, then trash a $35 carbide endmill an hour later, and repeat on a regular basis, it doesn't take long to figure out the trash that's out there as hot rolled flat today sorta needs to be kept confined to torch and welding work.

One thing I have noticed is that most all the trouble comes from the thicker stuff. I still use some 1/4" HR flat for some other parts and never seem to have any problems with it. I guess its easier to run the half melted stellite valve seats and such into the thicker stuff. Might mess up their rolls if they got too much trash in the thick stuff with nowhere for it to go.