I'm guessing this is the work of either Parkenfarker, or Bubba. Either way, it's top notch backyard gunsmithing! The objective was (I believe) to make their fine Ballard rifle into a "takedown rifle". How they accomplished that was very unique!
It's not a great picture, so here's an explanation. Someone removed the lever and breech block halves, and then used a hacksaw to cut down through the bottom of the receiver almost to the threads on the barrel shank! Guessing that at this point the cut was close enough that receiver either split; or they possibly put a wedge in to complete the cut. The threads weren't cut, but bottom of the barrel was nicked where the hacksaw blade hit it while cutting.
I put the barreled action in my barrel vise and using my action wrench I gave it a good tug and it didn't loosen. But after loosening the home built tension screw pulling the cut tightly together, the barrel spun off by hand easily!
A nice special order pistol gripped, forged Ballard! Loop lever and all matching numbers. Now unfortunately nothing but parts if I can't come across a donor receiver, or a talented welder who can repair it. Anyone know somebody who can weld it, or has a forged pistol grip receiver, give me a holler!