SpudFiles

When ever I want to purchase barrel tube I can get whatever size o.d with a given wall thickness, this is fine as I can calculate what size I need. I can get either metric or imperial barrel and tube and ball bearings.

But tolerances/innacuracies never seem to go in my favour, I could buy 10mm internal barrell and 10 mm ball bearings and you can be sure they will not fit properly, and expensive bearings made to standards (not slingshot junk) cost a fortune.

How dl you get around this? Or am I just unlucky?

Id buy lead balls and use something to patch them, rifled barrel or not.

They make all different sizes of lead balls and they will usually pancake on impact instead of bouncing back atcha'.

Use some kind of cloth or paper and go to town.

If you want good tolerances unfortunately you have to pay. An alternative as suggested is to use softer projectiles that have a bit of "give" and therefore will fit the barrel well in spite of slight differences.