The break open action tends to operate best with a cartridge that has a rim, allowing headspacing there instead of the shoulder. The rim aids in reloading to minimize case stretch.
I settled on the .307 Winchester as the parent case, and having long been a fan of the quarter bore, decided on .25 caliber for the round. I had the work done by Kim at Chase Mountain Custom. We decided on a "stub" barrel set up, which is taking a donor barrel and cutting it off just forward of the attachment lug, boring it out and threading a barrel blank to fit, this allow for chambering the new round to fit. The barrel we chose is a Pac Nor Polygonal, Full Varmint Contour.
Here is the rifle as received from Kim.
The parent case, the fireformed version, beside a .243 case for scale.
The first target that I produced. 100 yard 5 shot group. I had a one holer going till I choked and pulled the last shot.
Deciding to go synthetic for a working stock, I purchased a shotgun forearm, used a deep well socket covered with sandpaper to relieve the channel to the proper dimension for free floating, then threaded in pillars and used Devcon to bed the pillar area.
First game taken.
