Re: who can make me a tight bore 6.5 blank?
The point of a tightbore 30c blank is to get extra speed from the anemic case capacity of the 308 in various forms of shooting as it aids in obturation. Shorter barrels on rifles that are meant for tactical applications, long barreled rifles meant for getting to 1k as quick as possible for things like F T/R, etc. How often do you find a tightbore 300 magnum used? Even for regular builds that aren't 30" barreled bench rifles, I've yet to find someone with a 30-06, 300WM, 300 Wby, etc. that's built on a 0.298/.308 barrel.
The 6.5's in 22" trim would be the way to keep a barrel slightly shorter on a 260 and get slightly better speed numbers. I have some reservations about the end all precision that can be gleaned from tightbores. Some have shown to shoot very well, but the vast majority of tight bores are found on 16.1-20" 308's shooting at longer ranges, 800+yd. The targets engaged are generally for tactical comps or actual field use and not usually shot to chase miniscule groups at those distances.
Lead is essentially a dead material. It has almost no elastic restitution, annealed gilding metal isn't much better. Therefore, if you take a precision bullet that's been been swaged into a match quality product and shove it down a tube that's 0.001-0.003" smaller than it's meant to be shoved through you run the risks of really F'ing with the bullet's repeatability.
Slightly tight bores and tapered bores are relatively common in Rimfire BR rifles and if you look at what Brux offers, they have a tightbore 30c option, a 22c centerfire and a tightbore 22 RF option. It is well known in the rimfire BR game that you can make a barrel TOO tight and it won't shoot to snuff.
If the OP was asking for a 16.5" 260Rem for a truck rifle or a duty rifle then I'd understand more, but at 22" I think it's going to be a waste of money.
Also, the tightbores out there are a function of how big the bore is to begin with. The tight 22's are 0.001" under bore with the grooves being 0.0002-.0004" under. The 30c centerfire barrels are -0.002" bore and either dead on grooves or -0.001".
Assuming you're going to go forward with this project (and as cautionary as I've been here, I'd like to hear how it works out, even if it means eating my words), I think that a -0.003"/-0.001" barrel on a 6.5mm is going to be VERY tight.
