Optimal Cast Boolit Design for Gain Twist Barrels?

[Z.F.Bowles]

Put it off for awhile but I'm working on getting casting for my 1918 Carcano. As you may know, Carcano rifles this era had gain twist barrels. Looking at artillery shells for artillery guns with gain twist barrels, they all have a very short drive band at the rear and the rest of the shell is a bore rider. I think I'll use this in my design as there's not much available on Gain Twist in normal rifles but was wondering if it is thought it would be better to have a few very short driving bands with lube grooves or one longer .250"? driving band powder coated with no lube groove. Have the stuff to powder coat already.

I believe there is possibly inherent issues in using the Lee Cruise Missile bullet in a gain twist barrel because of the distance between front and rear most drive bands twisting at different angles and wanting to be turning two different rotational speeds. Which may explain why some people have poor accuracy and see a drastic improvement when the mold is shortened? I'm imagining that the distance between lands or grooves would be the optimal length of the driving band? Of course that's just how i am visualizing it. Am I over thinking this or am I right? Or wrong?

[popper]

What is the gain in twist? per boolit length? I was surprised at the torsional strength of long 30 cal cast, Twisted with vise-grips at either end, takes a lot to break and they always broke at the l.g. As stability is really dependent on LENGTH not weight, my guess the cruise works better shorter as the main twist is basically too slow anyway. Run the numbers and see how it works. Original rifle was designed for RN then changed to spitzer so band length shouldn't be the problem.

[MT Chambers]

I don't believe it is a concern, many shuetzen shooters use Ron Smith's gain twist barrels with cast boolits only (usually breech seated), their results speak for themselves. I wouldn't over think this, guys like Smith, and Pope, Roberts, Hudson et. all beat us to it.