I would look at the Savage F-Class rifle. It is chambered in 6BR with a 30" 1-8 twist barrel. It's a single shot and the barrel is 1" at the muzzle. The only thing that needs to be done to it, is to have a front stud installed so you can use a bi-pod while out in the field. My firend has a Savage F-Class in 6BR and it groups in the .3's with ease.