Thank you Moleman for the pics. I know these were in your original post, but under this discussion and context I was now able to make the connection with my feed issue and how you resolved it.
Armed with this new perspective I decided to add a couple more dummy rounds to the mix. I was going to solder on a piece of .022 feeler guage to build up the lifter neck similar to Molemans pictured example. I am using all the same brass stamp for my testing. I only hads already loaded rounds so I decided to shoot them to recover the empty cases and the build additional dummy rounds. After all the whole point is to use the rifle as much as possible. Well I loaded 2 rounds in the mag tube. Racked the first one in and it hung up a little even though this was a pointy 150 gr PSP bullet. But it was coaxed in easy enough. I fired that round off. Then I cleanly racked in the second round and pulled the trigger. It just did not "feel" right. That is when I discovered my new issue. The mag tube had completely worked loose and was now extended beyond the barrel.
I should have seen this one coming. The 357 barrel contour is much smaller. The holes for the band which normally keeps everything aligned do not sit as close together and it allowed the mag tube to slip past the band screw under recoil. Since I shortened the mag tube the other barrel band is not there to keep it all in place. So out it came.
So I spent the rest of the evening trying to come up with a method to keep the mag tub in place in relation to the barrel. I got my initial plan that involved an old Mauser stock swivel modified to work as a kind of trunion and affixed to the Mag Tube to close the gap and seat firmly in the screw channel cut into the barrel. I am still tweaking the exact placement to get everything to line up, but should have a workable solution soon to at least work around the issue to continue on the with the project. If I need to rework my mag tub idea I can always buy a new tube and reconfigure.
I knew I would face problems so not a big deal. I am still confident of eventual success.
Last night worked on this some more. Just the Mag tube. This turned into a real pain and took 2 evenings of work, but I finally got everything lined up and in place. As a bonus I might have even solved the original problem! It took a lot of finesse fitting to get the cross screw to cleanly go back through and lock the mag tub in. I had to a lot of fitting on the band, barrel, mag tube and my soldered on trunion to get all line up. I do not have a complete set of pictures for this yet. I was way to involved in the file, fit, and don't screw it up process to get anymore. Now that I have it working I will take some to show all the areas I had to work to get it to work.
Here at lease is a couple that I took when I started.
First I filed a flat for the trunion to sit on. This had to be position roughly where the bolt groove used to be. I did it with a fine file and took my time to keep it as flat as possible.
Still Working on this, but not as much. Deer season 2019 is rapidly approaching and I am getting ready for that plus I finally received my iron sights for the M95 Mauser 35 Rem project and I have been spending a lot of time getting that sorted out. I will get this project going again once I clear out some other open projects. I was kinda hoping to have it for this deer season, but I don't think that is going to be possible.
Got some time today to work on this project. I used a unknown combo wrench as my donor. It is .1 inch thick. I traced the shape and then used a cutting disc to rough it out. I used a combination of files, diamond bits and stone to tune the shape. I will affix to the lifter as Moleman did on his conversion.
I have also built up the left side of the gate as viewed from the U shaped gate end of the lifter. This appeared to resolve a great deal of feed issues of the cartridge going into the chamber. As it stands this evening I was able to feed 15 cartridges without a jam going from the mag tube, to the lifter and into the chamber with my big fat round bullets. I have test cartridges with 150 psp bullets and those did not do so well. They were not making it through the now built up gate from the mag tube. Looks like I might have to bend the lifter back down a little. I still have to deepen the ejector and extractor slots on the bolt. As it stands now extraction is pretty good. Ejection of test rounds, eh... not so much.
I am putting this project down for a while. I need to focus on getting my deer rifles ready and setting up my blind and climber this weekend. Next weekend and beyond for the next several weeks is Bambi chasing time. I will pick this one up after season is over and really start to work on it some more.
I guess if I can get one or two bullet profiles to cycle well it is still a victory. This has not been an easy conversion.