Alloy?
It's a good alloy! It can handle high pressure, is easily machinable, all that other rubbish.
Now, if you would kindly tell us what bloody KIND of bloody barrel you are talking about, instead of just saying "barrel' - well, that would be a help. Otherwise, it's just completely useless.
For something that isn't completely useless, please see below. We bought a whole bloody lot of the stuff to do these things with, and it's still taking up most of my living room.