I recently bought an H&R 38 55 Target Model. I almost ordered a .379 Lee mold from midway so I could reload this round. I used Lee dies, also new. The paper in the die case and the sizer die says 38 55 but the expander and seater die says 375 win. After today I don't know if I will go with .379 lead bullets or not, probably not. Here's why:
Today I got the reloading bug and tried to reload some ammo for it. I bought some .379 Brass Plus lead bullets from Midway recently. I did not size the once fired Winchester brass since the brass was smaller than the bullet. I loaded 10 cases and seated them to the the crimp groove.I used a light crimp, just enough to reduce the flare. None of them would chamber in my gun.
I can force the gun closed but the round is stuck. I did not fire any of these reloads. I have not slugged my barrel but a 3/8 drill bit that measures .375 will enter the chamber without any problem, it will also go in the end of the barrel. The once fired empty cases will go back in the gun with no problem. With a vernier caliper I cannot tell the difference in size when comparing them with factory ammo. The rim end measures .414 at the head on both reloads and factory, the only difference I find is at the bullet end of the case, factory is .394 and my reloads is .396. I can't believe that the chamber in my gun is cut that tight.
I am doing something wrong I guess but right now I don't know what it is.
My advice is check it out good if you are going to reload, Barnes makes a .375 and .377 jacketed bullet but they are too expensive for general reloading in my opinion. I guess if you are going to hunt with it, a bullet is a small expense in deer hunting. I just wanted a plinker load more or less, that don't cost a dollar a pop. I used 9.5 grains of Unique in this load, that I found in the 47th Lyman Manual, for a 249 grain bullet. My bullets from midway are 255 grains.
I hope this gives you some insight into reloading the 38 55. It looks like to me that this will be a challenge.
Just my 2 cents, I'm trying to learn. Hope you get a lot of info off the board.