[FrankenMauser]

If it isn't tacky, doesn't feel gummy if you hold it for 10-15 minutes, isn't going to stick to anything or pick up any debris, and won't stick to the case or imprint the pattern of the material while in transport, it's probably fine to shoot.

But if you aren't sure, don't try it.
You won't be doing yourself any favors if you screw it up and have to wait for it to cure, just so you can sand it back and start all over.