If you have read our Cyborg Barracks guide, you already know some mobs inside drop Soldier only weapons. The only problem with them, as with any equipment, is that you outlevel them. The solution is to upgrade them although a bad side-effect of this is that they get a much higher level lock.
So what do you need for this task? A Hellfury Assault Cannon or a Hellspinner Shock Cannon, of course, and some special items dropping off high level raid mobs located in Eastern Foul Plains. Like always there is good and bad news. The good news is that you only need one item, depending on type of upgrade you want to make, and that these items have a high chance of dropping (90 to 100% dropchance). The bad news is that the mobs you need to kill to get your hands on these upgrades aren't exactly easy.
Once you have all the parts, assembling them is easy. You'll need 42 Weapon Smithing skill for Hellspinner Shock Cannon and 40 Weapon Smithing skill for Hellfury Assault Cannon. Note: Boosted versions have Level req of 175, Augmented ones of lvl 190.
For those that have already upgraded weapons to Boosted version and now want Augmented ones, there's easy sollution. There's no need to go camping for basic weapons, but you can upgrade them from Boosted ones with proper add-ons.