I think the thickest part of the barrel is 1mm and they're about 0.5mm at the tip. To get decent results machining the brass like this is the only way to go! In the past I did try gluing sections of styrene rod of those diameters together, but it was difficult to get decent results that were straight.
There's not actually anything difficult about doing the machining itself, but unless you score a secondhand lathe for dirt cheap like I did it can be very expensive to get set up
Oh yeah I can make that....