Print at .1 layers for the best chance of threads to work better as they are pretty tightly toleranced. May need to be scaled up to fit whatever caliber bullet you want to fit but works great at normal size if want the Jurassic Park Barbosal Prop. Threads do not require support. The only part that does is the nozzle at the top and the grooves near it.
Printed in FIllamentum Vertigo Grey PLA.