I am pondering putting a pacnor polybore on my 7mm STW I am building. I was wondering if you guys had any input on the accuracy of these barrels. Good, bad, or fair? I am planning on making shots up to 850 yards and want a good barrel, but I shoot a lot and I am sure I won't have to worry about burning a polybore up. Just need it to be accurate. TIA

Ill bite , whats a polybore? Dont see any mention on pacnor's web site

I'm sure as hell not qualified the way the rest of you are, but I think I can answer this one. Pretty certain he's referring to polygonal rifling. The lightbulb will go probably go on for you in a moment, but if not, H&K sites/boards typically address the pros/cons. The general idea is that instead of rifling thats cut or swaged(?) into the barrel - complete with sharp edges etc. Polygonal rifling is supposed to be "smoother", resulting in less friction, higher velocities, greater wear resistance, greater accuracy. One drawback is that one will typically get alot of leading if using cast lead bullets. (See Glock kaboom arguments - they too have polygonal rifled barrels). This leading issue is also cause for significant debate, but I've personally experienced it in several Glocks (no kabooms though), so no lead bullets in my stock barreled Glocks or H&K's.

Ah, polygonal

Sorry 7mmSTW, I failed to address your question. I should have also mentioned I have no experience with PacNor barrels. Again, I'm no expert, but given that benchrest shooters are probably about the most anal shooters out there, given the distances you intend to work with, I'd lean heavily towards whatever they're typically using. If it's poly, go for it.

Here's a wiki link for a little more background (although for what its worth, some of whats in there seems to not jive with previous memory).

http://en.wikipedia.org/wiki/Polygonal_rifling

Before you decide on an Pacnor polygonal, be aware that Krieger now offer Obermeyer 5r rifling option
Same as an Mike Rock.
http://yarchive.net/gun/barrel/polygonal_rifling.html ...

I have used some polygonal rifled barrels in the past (Shilen DGA, H-K)and they worked OK but I never had one which was BR accurate. Fine for a hunting rifle but certainly no advantage to it. There was always some difficulty in getting them clean. I have yet to see any difinitive, unbiased study which indicates any rifling form is demonstrably superior to what would be considered "conventional" rifling.
The Shilen "Ratchet" rifling is a sort of modified polygon and does seem to shoot as well as any other and cleans better than the DGA did. I like the one I'm using now just fine. I don't see any advantage to it though. It's just a bit different. Regards, Bill