In regards to the Encore and the "short mags".
I don't know of any barrel makers making the short mags at this time for the Encore. I know a couple tried at first and they did not work out so well. Something about the case resting on the shoulder in a single shot.
If you want the best barrel (no matter the caliber) and you reload, I would look at OTT for a custom barrel. You send them two dumby rounds loaded on your press with your dies. They make a chamber from the rounds so that you can get the best fit and accuracy.
Here is a recent article about OTT's work along with Mike Bellm of BellmTCS on making a .2 MOA 6mmBR Encore...
http://www.6mmbr.com/gunweek055.html
OTT can be found at...
http://www.ottllc.com/
After I get my turkey barrel for my Encore my next barrel will be a pistol barrel from Mike at OTT.