judging by the fact that your air rifle purchase has just fallen though would you be planning on making what i think you're planning on making? if so, then two things, firstly they're illegal, secondly, rather than trying to bore a hole down the centre a piece of timber you'd be much better off splitting your piece of timber and carving a groove out of the two pieces that you end up with, you can then get a piece of copper pipe (from wickes) and sandwich it between the two halves of your stick (you'll need something to fill in the inevitable gaps between copper and wood, there's many ways you could do this from epoxy to pine resin and anything in between) glue and bind the stick back together and hey presto you've got your 6' long stick with a hole in (whatever you may need such a thing for!)
be safe
stuart