I bought a few of these several years back and initially slugged the bores cleaned them up and oiled them. I had been reading about converting them to centerfire, forming cases etc.
I got a few other old BPCR in between then and got those up and running, neglecting the Vetterlis.
Now that the winter has set in and it's a good time to spend in the reloading room, I got things set up to start working on loads for the Vetterlis.
I had a mold that I had ordered from Accurate a few years back, and a bunch of 348 cases I bought to form the brass with. A Lee die set was used to form some cases and I found that they stuck out of the chamber just under a tenth of an inch or so after forming. I had read about people filing down the back end of the case, but I wasn't really to enthused about filing down 40 or so cases. I had found a few spent 348 cases at the range I go to, so I drilled out the base, cut some grooves around the rear of case, and secured some threaded rod in it so I could chuck it up in a hand drill. I honed out the rear of the chamber by applying 320 grit Clover compound so that the formed cases would fit in there. This was a $150.00 Vetterli I got from somebody on Gunboards, so it's not like was too worried about it losing any value.
I will note here that I also had trouble seating the cartridge formed with the Lee die in the other rifles. Leaving them a bit long to compensate for shrinkage in fireforming allows them to get hung up in the taper at the front of the chamber. I did pickup a used set of RCBS .41 Swiss dies on the cheap (well, relatively cheap), and running the cases through the RCBS sizing die take them down a bit more so there was no problem getting them to chamber after that.
A hole was drilled in the bolt face, and a carrier made with a decapping pin sized and shaped appropriately.
I left the brass a little long when I first cut it so that I would have enough left to work with when I got around to fireforming them. As it turned out there was plenty of brass left as the OAL of the cases after fireforming was only .005" or so shorter. 12 gr. of Unique, some corn meal, and Elmer's glue to hold the contents in was what I used. I took the rifle out to my garage to fireform the brass. I filled an old plastic 5 gal. pail with old towels so as to keep the noise down. Ended up shredding up the towels in the bottom pretty good and cracking the bottom of the bucket...
With my cast boolits sized at .435" I started experimenting with a length. I settled on 1.650" to start. Once I had the length, I reamed out the inside of neck to about .433". I only had about .006" left in the case wall, and with a boolit seated it did have some resistance going in and extracting. I kept repeating this and checking fit until I got down to 1.630". I had opened up the reamer slightly so I was getting a dimension of .4335" on the case mouth, and the case walls were at .009", which is what my target was - I didn't really want go any less than that.
Seating the boolits until the OAL was 2.200" still allowed the edge of the mouth to fall within one of the grooves in boolit, so a slight but sufficient roll crimp would not dig in to the boolit.
I had some Blackhorn 209 available, so I loaded 33 gr, of that, with a lubed hard felt wad under the flat based ~330 gr. boolit. I drilled the flashholes out to .093" and primed with Federal 9 1/2 Mag primers to light it off. That load is slightly compressed. The boolit was cast with WW.
So I'll have to see how well it shoots with that combination. if we get a nice day weather wise soon I'll make a trip to the range to see how it does.