<<<Barrel length has to do with twist. If yer shooting round ball. The slower the twist and longer the barrel, the better you are. >>>
Only to a point -- the logical conclusion of what you just said would be that a straight rifle would be perfect. Not so. You need to stabilize the projectile with the correct twist for the size and shape involved.
<<< If you are shooting conicals. You want a faster
twist. >>>
Generally true, but I have a Lyman which is fast twist and still does well with round ball. Go figure.
<<<The ideal range for round ball is 1/66 to 1/72.>>>
This would be good for a .50. Smaller bores like a faster twist.
<<<I bet the 36 wieghts a tad less. I went with 42 because I wanted a "Longrifle" and maximun powder burn.>>>
I went with a 42 because I liked the look and I liked the long sight radius. The modern powders are still pretty good and do not need the extra barrel.
<<< Your talking about a TVM which is a store bought. You get what they give you. >>>
This is not true, I bought a kit gun made to my specs for a reasonable price from Matt and Toni. They sell kits, in the white and finished guns. Spoke with them the other day and this is still true. You may need to wait for a while, but quality is worth a bit of a wait. Their barrels are Green Mtn or LongHammock. I have 3 Gr Mtns and one LongHammock -- no complaints.
You can see the guns at:
http://www.avsia.com/tvm/virginia.htm
CS