These syringes are glass and the needles are very thin, much thinner than a round toothpick. They're short needles but the glass can be ground down or the sharps can be removed from the glass.
I use them for carrying and disbursing oil and they have a thick rubber cap. These needles have such thin tubes that sometimes they'll get clogged with micro telfon particles that are mixed in with a teflon oil that I sometimes use.
And these needles can always be used to clear the nipples from their flat interior end without their short length being a problem.
I'm not sure, but if using needles that are thin, smooth and flexible enough like these should be, I wouldn't be concerned about wearing out the walls of the nipple hole. It's being done gently, the diameter is small and creating relatively little friction which would be far less potentially damaging than a hammer falling on the cone repeatedly.
I think that more damage to the nipples would occur due to gas cutting
than from using thin enough and flexible wire that's highly polished.
Hoppes makes some thin nipple picks too for an inexpensive price if they can still be found.
They're thin enough to snap in half and they have spiral grooves like a tiny mini-drill to collect the caked on deposits as it's being pushed & twisted through the flash hole.
