Sendero accuracy prob/questions??

[Dust270WSM]

I bought a 7mmSTW Sendero used a year ago and I am having a little trouble getting it to shoot a tight group...I reload and i am using nosler brass with federal 215 primers.
I am wanting to shoot 168 grain bullets threw it. I'm not sure what the twist rate is on the remington senderos? But I am getting better groups with the factory 140 grain nosler partions than I'm getting with reloads.
I have tried the new reloader p0wdsr a long with h1000, ramshot magnum and imr7828 a.c.. a long with changing the bullet length. Bullets I have tried are bergers, nosler and now hornadys 168s. All producing about a 1" group which is not bad but it shoots 1/2" groups or smaller with 140s...so question is...Where would u guys or gals go from here.
Also it has vortex viper pst scope on it with night force bases and rings also bedded the recoil lug...

 

[MudRunner2005]

The twist should be 1:9.25". I would try seating the bullets around .015" off the lands, and see if that helps.

I have 2 7mm STW Senderos (factory Sendero SF, custom Sendero blueprinted). They both have 9.25" twist barrels. I haven't shot the custom yet, although I've had it since 2014... But the factory Sendero SF shoots Berger 180 Hybrids into .4" groups average using Nosler brass, Fed 215M, 7828 SSC powder, with the bullets seated .015" off the lands.

 

[Dust270WSM]

My bdl box is to short to get it that close to the lands...think that's one of the pr0b also.

 

[MudRunner2005]

My bdl box is to short to get it that close to the lands...think that's one of the pr0b also.

Mine too, so I shoot them single-shot.

You could solve this problem by installing a Wyatt's Outdoors 4.000" extended mag box and follower. It will have to be installed by a professional gunsmith, as it requires milling out the stock and part of the bottom of the receiver.