I am very close to machining parts for my rimfire prototype. I've made a couple of wood model action bodies to work bugs out of my programs without wearing out cutters and wasting expensive steel. Anyway, I am designing the barrel assembly ( barrel profile, ribs and sight bases) and am curious to hear your opinions on barrel length for a 22lr double. I have read that anything over 16 inches offers no benefit for velocity. That being said, for the versatility of my design to be used with 22wmr and 17hmr rounds, I am leaning towards using 18" or 20" barrels.

Please let me know your opinions!!