SpudFiles

yeah, I guess I should have used the term 'irregular objects'


anyway... if you don't want to 'catch' the sabot it might be a good idea to use something that is cheap and easily available

A pvc endcap probably meets both criteria

But I am sure there are a lot of other things that can be used for this purpose and are cheaper and/or better

You could also add some form of "choke" at the muzzle, say a series of o-rings, that would slow down the sabot, aiding projectile separation and lowering the potential for damage so it can be re-used.