Any advice on a good caliber to choose for a encore 15" barrel? Looking to hunt south Texas whitetails and hogs with it. How does the shorter barrel affect ballistics and performane compared to full 22 & 24 inch barrels?

For the deer-hog combo you are looking for, I'd have to say the .260, 7mm-08 or .308 will do the job quite well, and if you are a non-reloader, the 7mm-08 has lots of excellent factory ammo available.

In a relatively efficient case, you don't lose significant velocity in going from 22-23 inches of barrel length to 15 inches. In the .260, you can safely achieve 2700 fps with a 120 grain bullet and right at 2600 fps with a 140 grainer in the 7mm-08. A 150 grainer in the .308 will do 2650 fps.

If Bobby says anything about a 6.5 listen to him.
I have a 15 inch 308 and 7-08 barrel and the 308 seems to be the most accurate by far, but that probably is just my particular barrels, I have neard of some impressive accuracy out of some of the 7-08 barrels. My 7-08 barrel usually shoots 2--2.5 inch groups but my 308 barrel shoots 1.00 inch groups with some under an inch quite often.

Steve E........

I have a .260 factory barrel. It's not the most accurate barrel I've owned, but still shoots everything under 2 MOA and a couple of loads w/ 120 nosler BTs at less that 3/4 MOA (3 shot groups) my best being slightly under 1/2". This is a killer gun on Antelope, muleys and blacktails. It pushes the 120s right at 2600 Fps