Anti-double feed ideas wanted

[sv490665]

I'm developing a CO2 powered sniper rifle for marbles, I have a really good design going so far, but I'm wondering if anyone has any bright ideas on some good ways to make it so each time i load a marble into the barrel it won't roll around. The way i will be loading marbles is from a tee in the barrel with a sliding bolt on the inside opening and closing the top of the tee. I looked at my paintball gun's anti-double feed mechanism but it will be difficult to replicate that working mainly with PVC. Anybody got any ideas? I'll donate spudbux to whoever gives me an idea that i decide to use . Pictures would be great too. Thanks!

[MrCrowley]

you could put a small ruber flap in the barrel just enough to stop the marble rolling around and it could act as a hop-up as well making the marble spin.

[L.J.R]

Put a small bead of rubber glue on the top and bottom of your barrell, Rubber glue is the stuff used to repair bike tires.

[pyromanic13]

screw some paintball detents in it

[-T0OL-]

The spring would be stiff enough to stop the ball from rolling over it but not to stop it from firing.