The bummer about the whole thing, is that unless you make yourself a homebrew bolt, or turn down a PGP bolt, they usually don't fit in anything smaller than .687
I actually found some .750/.687 tubing at ACE not too long ago. A 3' stick run me about $16. I think this is the same size that McMaster carries.
Onlinemetals.com carries some that is .750/.685. I bought some of the 4130 CrMo to build my PGPs....It really is just a bit on the tight side for a paintball...(Which isn't so bad for the paintball, not good for the bolt.) I ended up flex honing it to about .688 or so.
In the future, I'm going to use some of the .750 i.d. 4130 and line it with the brass...(the brass I have only has .029 walls, kinda thin) The other idea I had was to get some Freak inserts and put them inside some .750 tubing. When I found out that the tip end of a Freak barrel is .700, I though "why not"
Catchya on the Flip Side.....
Emerald Wolf -- Onlinemetals does carry the correct size (in 4130 CrMo) for valve tube though....(Cart valves fit good and snug in it.)
