https://www.bing.com/search?q=billet&cvid=11978e1bb2e84e148e0a89bba3eef3b1&FORM=ANNTA1&PC=U531
Billet can be anything that is machined from one piece. It may be a billet of forged material?
A billet is a solid block of aluminum (or any material) with the size depending on the size of your...
Just using a die and taping can and usually does give a crooked thread. It should be done in a lathe with the tail stock used to support the die while the barrel is in the lathe chuck and centered. Should be a 4 jaw chuck with a spider at the other end of the spindle.
Only way to guarantee...
https://www.portlandbolt.com/technical/bolt-torque-chart/
Lots of info, torque according to size and grade of bolt. Several different grades listed. Always use the lightest torque value if bolt grade is unknown.
I have no clue what grade bolt you have.