SpudFiles

sry for such a newbish question, but how tighly does your 'ammo' have to fit in the barrel?
should it be exactly the same diameter as the barrel? or should it be slightly larger? or smaller?
do tight fits work best?

thanks

depends on the ammo if you'r using spuds they fit pretty damn tight. You have to estimate what kind of ammo you're using for what diameter.

Good luck fitting something (much) larger than the bore diameter in the barrel.

That having been said, though, some generalizations I got from toying around with the GGDT:
The acctual value of preformance lost for a certain size differance (bore-projectile) stays about the same with the same projectile mass. However, better valve systems/larger chambers increase preformance, making the percentage of preformance loss smaller.
Lower mass projectiles are affected less by size differance, such as my (arguably extream) case when firing saboted paintballs; a diferance of 4% with projectile that fits as ill as -1/8" in a 1.3" bore (10%).

I have some cheap tennis balls that have a looser than normal fit and they go much further ,but with spuds the tighter ones seem to go further.

i think thats a good question, the variables are many, and the answers can be many, take your question apart and answer/research the topics 1 at a time, will take longer to figure it out technicly speaking

THE EASY MATH----do your research in the field, try different fits every time you shoot your cannon

then post your results so we can compair and learn

The affects of "blow-by", something I am soon to be testing. Obviously a tight fitting ammo wont go as far because of friction, but a loose fitting ammo wont go as far because of "blow-by" (basically energy is not all concentrated on ammo, but rather taking the easyer path, which would be around the projectile). So as of right know I think a .01 to a .02 difference in the barrel and the ammo will be the best, but I dont have any tests backing me up yet. In theory I would belive that the number of difference would be much smaller to provide the best result, but due to irregularites in both the projectile and barrel the number is larger.