opinions on tight bores and accuracy?

[constructor]

I've heard that tight bores with small dia bullets like Lapuas are more accurate but I 've also talked to a barrel maker that says low profile lands increase accuracy possibly because they deform the bullets less. What do you guys think?
Do tight bores or 3 wide lands increase pressure?
Also heard that Pac Nors are slightly smaller than most barrels on ave. any truth to that and are they beneficial when shooting Lapuas?
I am shooting some of these but it may take a while to get enough results to form an opinion so I thought I'd ask the pros here. Thanks

 

[flatlander]

I've had several 3-groove PacNors in the past, and currently shoot Krieger & Bartlein 4-groove bbls. The PacNors I chambered did not have a tighter bore than the .236" Kriegers, based on the reamer pilots I used. My Bartlein 6mm bbls. have all been ordered with .237" bores, while all the Kriegers are .236".

From what I saw with .224, 6mm & 7mm 3-groove bbls., I believe the wide lands of these barrels do offer additional resistence to engraving jackets,relative to a 4-groove bbl. with narrower lands) to the extent that, as a general rule, they'll reach max pressure at a lower velocity than a 4-groove bbl. with the same bore dia. There are exceptions to every 'rule of thumb', and my experience with a dozen or so barrels doesn't constitute any sort of scientific valid experiment. I'm just reporting what I've seen.

The only comparison between .236" & .237" bore 6mm bbls. I have is with a couple of 6x47 Lapuas - one a 7.5-twist .236", the other an 8-twist .237". They were both chambered with the same reamer. It's no surprise to me that the .237"/8-twist is over 100fps faster with 115gr. bullets than the .236"-7.5-twist, but if we took two more barrels with the same bore dia. & twist and tested them against each other, there's no guarentee that we'd get the same results again. Whatever - they're both drop-dead accurate at 1000yds., so I'm not going to fuss much over the velocity difference.