I have something very similar, in that I did a "stub" Encore in .25 X .307 AI. I used a Pac Nor Polygonal 26" barrel, and have a wonderfully accurate shooter that lets me see the impact. I like the rim for the break action.
Left .307 parent case, center fireformed .25 X .307, .243 for reference.
120 gr. Sierra, I just showed the front half, because the back half was a mess.
Groceries!