I've wanted something like this for years.
I finally am getting a Contender barrel made, with twist & dia recommendations from C E 'Ed' Harris.
The waiting is killing me!
Already thinking about the next project - I have a .303 barrel from a No 4 Mk1 that I cut a releif groove around to remove for a 45 ACP project & have a small pre-war "44 shot" H&R's, but it has full-cock issues.
My big problem is - No Time!
Regards -
Russ