10 twist seems a bit slow for a 7mm barrel. With that twist you may be limited to 140 grain pills or lighter, which means you will have great velocity numbers, but if you are looking to take a long poke at something, you could be at a disadvantage.
I could not agree more.
I have a Wby Ultra Lightweight MkV in 7mm Wby mag with a 1-10" twist. It shoots:
* the 140gr TTSXs really well (1/2"-3/4" at 100 yds);
* won't group well with the 150gr NBTs (over 2");
* does not group well with any of numerous 160gr bullets I have tried, except for the the CorBon-loaded 160gr TSXs (those are under an inch).
I shot some Federal-loaded 160gr Trophy Bonded Tips that came out at 3,219 fps, and they grouped over 2". When I looked at the target carefully, I noticed that the bullet holes were oval-shaped, which means that the bullets were hitting the 100 yd target at an angle.
Fortunately, the rifle will do what I need with the 140gr TTSXs (3,280 fps MV) and the 160gr TSXs (3,240 fps MV), and it is nicely accurate with those, but I would much rather be able to accurately fire the 3,219 fps higher-B.C. 160gr TBTs.
I would MUCH rather have it with a 1-9: or 1-9.5" twist, like most 7mm mag rifles have.
Kind of disappointing that Wby made that rifle with too slow of a twist to use most of the bullets available for the caliber--and I tend to like heavy-for-caliber bullets. This is especially odd given that four of the six of the 7mm Wby cartridges that Wby manufactures (weighing between 150gr and 175gr) do not work in Wby's own rifles.
1-10" twist for 7mm seems debilitatingly too slow for 7mm rifles.
I love Wby rifles, but that was a mistake.
YMMV.
