RE: Which barrel maker?
I'll have to contact my brother to ask the name - as I can't recall it just now. There is a custom shop in Alexandria, MN that is known primarily for working on Ruger #1's, that has quite a few Encore barrels he creates as well. Just can't remember the name right now - maybe James B knows.
Have you shot an Encore with rifle barrels much? If so, wondering how your accuracy has been. I've only used my Encore in ML form, so I have no experience with rifle calibers. I've have one hunting aquaintance who was not that complimentary with his experience - just wondering if it has worked for others.
IMO, I think I would go for a non-standard caliber in an Encore barrel, since it will be 'custom' to start with - being left handed, I don't have as many options in calibers as a RH shooter in bolts. A 250-300 AI would be interesting to me. I have no quarter bore yet, so that's part of the reason - I see you have that space open as well. Being located in South Dakota I would think your shooting could be at extended ranges, and the 250-300 AI should accomodate that.
Other thoughts - would you like a larger caliber? 35 Whelan is interesting - may or may not be the most useful in SD.
And as a side option, if you ended up wanting to sell either of the barrels later on for half price I would be standin 'n line - LOL.