Not this again...
HPLV is NOT the way to go, you need to accelerate it slowly, over a long distance
Rifling a paintball actually does work, other people have tested it, sorry no links, but in the end you are shooting a projectile made of jell-o, cough-syrup, and crayon wax, don't expect one hole groups at 80 yards... or 50... be happy if you stack them at 30...
the whole "paint-to-bore match" is to apply even pressure on all sides of the ball so it generates as little spin as possible, often compared to a "knuckleball", by the time you've added the sabot you don't need to worry so much about paint-to-bore match.
a sabot with a "Skirt" that expands to prevent air from being wasted as blow-by and, if applicable, allows the projectile to "bite" the rifling, would be ideal, be sure to use low-friction materials.
Rag should be able to get you the ideal ROT for a rifled barrel, and a good rifling bench isn't that hard to make.
remember that the barrel accounts for 50% of the accuracy, don't cheap out on the tool that makes the barrel.
now, for those of you who are wondering what happened to me making rifled barrels:
it can be done, it does work, but it's a waste of time, effort, money, and... well... it's pointless...
for the barrels to work you'd have to have a custom valve: low pressure, low flow, low turbulence, highly consistent, with dwell that is infinitely adjustable, and to make it work best the valve pressure would also have to be adjusted mid firing.
never mind the fact that the barrel would have to be ungodly long, and it would have to be heavy to keep it stable.
having seen the capabilities of properly honed brass barrel (PPS) I feel rifling an unnecessary complication (this from the guy the likes Autocockers due to their complexities, and runs Co2 for the challenge)
this is not to say that I won't be making a paintball rifle just so I can say "I told you so", this is to say, unless you completely understood everything, I just typed don't bother with rifling.
(I want this quoted every time anybody, myself included, brings up the subject of rifled paintball guns)
As for sabots in a smooth bore:
over complication that would see minimal effects and would prevent most any field from allowing it's use.
If I saw a gun at the field I work at that had a projectile other than field paint coming out the barrel I'd not let the owner use it in a game, to many safety concerns, insurance company would have a cow...
And if this is simply for target practice, there be infinity more accurate projectiles for that endeavor than cough-syrup filled jell-o balls...
as far as the "clip" fed cartridge aspect, go spend some time researching the Tippmann SMG 60 and the ATS series of guns...
this is the one part of you design that can be made to work easily, and will be slicker-than-all-get-out when you do get it to work, particularly in full-auto at 10bps/600rpm
and finally PVC barrel???
buy yourself some good brass barrel stock from Tymcneer:
Brass Tubing - M. Carter Brown
when/if you order from Ty, tell him the Judge sent 'ya. 8)
one more thing, do yourself a favor and use a good poppet valve for the main valve.
okay, time for bed, Ragnarok or JSR will more likely than not pick up on anything I missed/correct anything I got wrong...
