"Perry Murlless" wrote in message
...
Why not make some temporary seals for each end of the tube, fill it with
water, freeze it, mill it, defrost it??

Because the freezing water will change the size of the tubing, assuming it
can be well capped, and would start, almost immediately, to melt, leaving
the tubing with no support. Water expands too much upon freezing for that
to be successful, anyway Better choice would be a low temperature melting
alloy. Cerrobend, for example.

Using muriatic acid on brass leaches out the zinc. Bad idea.

Harold