First off....I am a big Weatherby fan, so I'm NOT knocking on Weatherby with this post. This is just my observations.
Weatherbys seem to be picky, from all I've read. My .257 Wby is not a picky gun. It likes the heavies, so I feed it 110 & 115gr bullets and it shoots ultra tight cloverleafs. I have noticed that most Weatherbys seem to like heavy bullets because they have a fast twist rate.
Believe it or not, I've found that alot of Vanguards won't shoot from the factory. The Sub-MOA's will, but alot of the regular Vanguards I've noticed alot of guys getting 1.5-2.5 MOA accuracy out of at 100. My buddy's Vanguard .300 Wby Mag for example shoots average 2.0 MOA groups. My Mark-V Accumark shoots 0.5 or less MOA groups. Granted, he could probably spend about $150 and have a smith bed the action, float the barrel, true the headspacing, etc... But still, we're talking about a $750 rifle shooting 2 MOA groups at 100 yards...IMO it should be doing better than that. I've got Remington's and old tang-safety Ruger 77's that shoot 1/2 MOA groups @ 100 and I paid half what he paid for that Vanguard.
I hope Weatherby has really stepped up their game on the S2's.
Has anyone had any luck getting one to shoot sub minute? I have tried three bullets and 6 powders, played with primers etc and I just can't get anything under 1 1/2". I know Weatherby guarantee is 1 1/2 minute but surely it will do better. I've done searches on multiple forums and haven't found much on the 7 Weatherby. This is on a Mark V deluxe, scoped with a Leupold VX 3 in Burris Signature Zee rings.
I have the same rifle in a 30-06 and easily 1/2 minute with IMR 4895 and a 150 Nosler BT. My .243, .223's and 30-30 I can get sub minute, so I know it isn't me.