marble rolling out barrel

[brumby]

Hi, I just finished making my first pnuematic gun and i realised a problem

The spud guns a small marble sniper type thing and I was wondering if there is any way to stop the marble rolling out the barrel when shooting?

thnx

[Hotwired]

How does it load?

If its a breech loader you could try using some kind of rubbery glue to make a small ridge inside the barrel just ahead of where its loaded which will stop it rolling forwards.

Needs to be small enough to allow the marble to easily get blasted out by the air when you fire it though.

If its a muzzle loader you could try putting some wadding round it before stuffing it in so its held more firmly.

[mark.f]

I use a small bead of shoe goo, (yes, that's actually the name of it), at the back of my 1/2" SCH-40 marble barrels. My 1/2" type M copper barrel doesn't need a ball-stop... the marbles don't roll unless the barrel's almost straight up and down and you wiggle it.

So... if nothing else, you can switch to a 1/2" type M copper tubing barrel.

[sgort87]

Point the barrel up.

[mark.f]

Yes, there's that, but if he lives in a populated area, you don't wanna hold the muzzle up much...

[POS]

I use the points out of a plastic bag, or just a piece of the plastic of a bag, folded into a cone. The marble fits in, and gets pushed to the back of the barrel, cone first. The plastic closes the very tight space between the marble and the barrel, giving it a perfect fit. When the marble exits the barrel when shot, the plastic cone will catch air and releases the marble, so the flight isn't altered in any way.