Hi all this is my first post. Okay I can have a rifle cut into a barrel at any twist rate I want, so I want to see if a cycloid can work for what I want. Now most twist rates are static so as an example one barrel may be 1 turn in 12 inches for 26 inches an example of what is called a gain twist or as I refer to it as a progressive twist rate the barrel might start or breech at 1 turn in 20 inches and finish at 1 turn in 8 inches at the the end or muzzle. Now I was trying tho think how would I calculate a cycloid along say a 30 inch barrel? So If I want one the barrel maker will want the parameters to input into the CNC lathe I just don't know how to calculate such a parameter. Also the barrel will be 7.62mm by 762mm long so 30 inch by .30 inch. I would be grateful for any assistance. The barrel design is for competition use I'm trying to see if a cycloid will be too aggressive on the bullet. Thanks. Shane. Edit I think I put this in the wrong section sorry.