Good luck with your Target Rifle and .38-55 conversion project. I posted last year about my Target Rifle so won't repeat it all, but will add that I've fired my second shot "in anger' and taken a second deer with it. Doe ran 35 yards and crashed after heart shot at about 55 yards range. Penetration complete, shot was on-target. I've reloaded a few rounds of .380/260g LRNFPGC in W-W and also in Starline brass, having to pay close attention to starting the gas check into the case. Also needed to "swage" most rounds after assembly by running them partway into the sizing die, and that allows them to chamber smoothly. Velocities with H4198 ran about 1640 fps with my first load. I didn't have a chance to really test for accuracy, but they seemed to print close to factory Ten-X Game Load ammo that I've taken both deer with to date.
I love the rifle, and I love the cartridge! It gives a lot of power but still has a comfortable recoil "push," rather than a sharp rap. The rifle is so slim and handy that I really enjoy taking it into the woods. I use the factory globe sights w/front sight post insert, and I feel very comfortable with the sight picture it gives me.