I have always had good luck with this. Possibly too hot or damp where you are painting?

They have also changed the formula.... so I was told.... Test this on a separate piece of metal, repeat a light coat at 12", and the next coat, let it be a little bit heavy...but not too much, it needs a" liquid surface", more then a "dusting" for the reaction to hammer finish.

At least, that is how I use to get the results I preferred on Slot machines.

Same for me. Possibly bad can?

I used it lately on a williams 1960's front door. Came out perfectly. It was a Rustoleum product. So simple I have to suspect your can was bad.

Why not have them powder coated silver vein?

Gotcha. If you want to do it I could turn them around same day, or if you wanted to take a ride, while you wait. Only take a couple hours.

The hammer tone paint requires a liquid surface and a fairly heavy coat of paint. When you spray the first coat, wait a minute or two and recoat a little heavier than the first coat.

I think the original "hammerite" was the better product they tried to copy. intended as machine paint, has fibers in it to make it tougher. it did have to be sprayed on pretty thick wet all at once for the beading reaction of black-silver-color and a clear to rise onto the top.
about 20 years ago built a tandem bicycle (easy welding project) painted it in green hammerite came out looking really nice. last tandem I built got rustoleum "hammered" coppery color, nowhere near as pleasing effect from the stuff.

I've only used the old stuff (pre-Rustoleum). I noticed that you can get a change in the pattern when you encounter ridges, raised surfaces or curves, etc. Other than that it worked really well for my Williams "Ten Strike" mannikin bowler.