[Orangekiwi]

Need some more advise please,

I just got hold of a nice piece of ironbark 110mmx25mm but have been told it is too heavy, and yes, at home it sinks when dropped in water. Still thinking of using 1 strip of laminate and use other timbers around it. Believe that being so hard would make an excellent spear rail groove.
Need the advise on wanting to know to what size you machine the strips before you laminate them?
Also want to know ( if I make a gun like arbalegno.com ) what size hole do you drill for the rubbers? Do you drill a 18mm hole if you use 18mm rubber or can the hole be smaller as the rubbers get stretched anyway?
Reason I am asking is that it looks like the muzzle end on this spear is going to end up pretty wide, 2x20mm for rubbers, approx 1 x 8mm for spear groove and have to allow for extra bits.

thanks,