Each can is named for its job, and the job decides the metal. Our rule is simple: the cheapest metal that does the job well.
The rule
Rimfire and pistol gas is mild, so those cans can be light. Rifle gas is hot, fast and abrasive, so those cans have to be tough. Paying for more metal than the job needs only puts the price up.
17-4 stainless steel
Mostly iron, with 17% chromium and 4% nickel, which is where the name comes from. Tough under heat and abuse, and cheap to make. It's the baffles in Proton Plinker and Proton Sidearm, and the whole of Proton Adapt and Proton Safari, blast baffle included. A worn blast baffle is replaced under warranty.
7075 aluminum
Light, and plenty strong for a tube where the pressure is far lower than a rifle's. It keeps Proton Plinker light on a rimfire, and keeps Proton Sidearm from making a handgun nose-heavy.
What we leave out
Titanium, Inconel and Stellite all have their place, and all of them cost more. None of our four cans needs them to do its job, so none of them uses them.