304 Stainless Steel is OK. But 316 is a much better choice. They are a bit stiffer then standard 304 Stainless. They are also a bit more expensive but worth it in the long run.
For what I need this for, I'm simply looking at the corrosion resistance. It's not for actual launch rods. At least not yet. It's for attaching to Mini and micro rails so they can be locked into launch pads.