First off, "WELDCOME TO THE WORLD'S GREATEST WELDING FORUM!!! :) :) :)"

Now, why don't you do a Google search in order to find out the information which shouldn't take too long to find? Please don't tell me that you already did because I know of many sites that will lead you to contact them (Heflin Steel) directly in order to have access to the classified information you seek... You need to be someone that they deal with in order to have access to this information. ;)

Okay, here's one of them:

http://www.escocorp.com/markets/aerospace_defense/defense.html

Here's their contact information:

Heflin Steel Supply Co
1111 W Maricopa Fwy
Phoenix, AZ
(602) 252-8941

What I know about this steel is that it is through hardened and NOT surface hardened as many have claimed... And it is a version of AR 500 steel probably made by another company which is the manufacturer of the steel such as HARDOX/ SSAB.

Well, that's about all I can do to steer you in the right direction because the rest is up to you. ;)

Respectfully,
Henry