That's more a matter of preference then anything. I personally only use shouldered barrels. There's pros and cons to each, but it's all subtle nuances that shouldn't make a difference down range, all else equal.
If not direct from @Zermatt Arms , try @Bugholes or @ALTUSSHOOTING Both of those companies rock and their customer service is top notch. The question is, what prefit? .......Thank you everyone.I'm going with the origin.I thought it would be the better choice and you have confirmed it.Now to find which vendor.