I'd like to flush/clean the barrel on my Hatfield percussion rifle with some sort of tubing fastened to the nipple. What size tubing would best fit the nipple on my rifle. I bought rubber tubing at Auto Zone, but it didn't even come close to a proper fit. Has anyone tried this instead of removing the barrel from the stock? The barrel flush kits sold by some companies don't mention nipple thread size, or size of the tubing.