Barrel Thief Leaking

[Bee]

I think the tip of this barrel thief is too big. Any ideas how to squeeze it down?
It leaks a lot when I pull it out of a barrel.

[acfixer69]

Are you sure it's not leaking air in from the connections? To reduce the fitting put a nail the diameter you want and just pinch it down with pliers, solder the seam or not.

[OtisT]

Easy would be to solder a small bit of copper to the tip with a hole the size you want (Or drill/file following the solder.)

Maybe a short piece of 3/8 tubing could be soldered inside the last reducer, like yet another reducer.

More difficult: Can you mount the back end of the thief in a drill press/mill/lathe? If so, and you are really handy and know how to work such machines, you could spin it and press the tip in from the sides.