You often have a choice of two different grades of bolts in most hardware stores. Some have more than two grades.

The regular grade is tough as steel. The will usually have stainless, but it's not necessarily tougher.

Ask the hardware guy for his highest grade and you'll get 6-32s that will be stronger than what you're using now. And what you're using is probably stronger than an ARF's two layers of liteply firewall.