I have an original Remington seater and other loading stuff marked 38 2 1/4 with a few old bullets cast long ago and dirty, no mold.  The grooved bullet mikes .378 and weighs 258 gr., a hollow based paper patch bullet is .370 and 254 gr.  The dipper is marked 50 on the handle, 5 cases, some headstamped 38-50 Rem.  The set is like the one in Chamberlain/Quigley's Reloading Tools of the Past page 42.  Looks like a Win/Marlin/Ballard mold would work if it casts .378 or so, would slug the barrel of course.  Hope this helps.    Jim Hays

The 38 2 1\4 is the 38-50 I believe. My bore slugs .379 - .380 or so. Don't think the chamber neck will be big enough to seat a bullet. So I'm either breech seating or shooting soft bullets and hoping for a bump up. Hate to modify an original chamber. But I am tempted to rechamber this or increase the neck diameter. 

Other idea is to paper patch like the original. Have wanted to try this. Will  have to find or make a different mold.

Jimmy,
I am currently working up an original RH in 40 2 1/2 and finding some of the same issues that you have.  Check my posting on Trying Paper Patch.  Last night I rolled my first paper patches and everything went well.  Bore fit is sweet.  I am expecting that I will be staying with PP.  It is probably what the rifle was built for and hopefully will shoot best.  If you get frustrated with your current barrel, my suggestion would be to get a replacement barrel and keep the original one.  A new barrel will have harder steel, be stronger, and should allow you to be safer using smokeless.  And you can still have a totally original RH.

If you go with a custom reamer have the neck made big enough for groove diameter bullets. The original chamber was not.

I still have not shot this hepburn. Maybe I'll try this weekend.

I have a 1:18 twist Atkinson and Marquette barrel on my .38-50 Remington Hepburn.
I blow out .30-40 Krag cases to make .38-50 cases. 
I load 50 grains Swiss FFFg with a .060 vegetable wad with newspaper over the flash hole and Magnum primers to shoot a 310 grain Boomer Money bullet. 
COAL is 3.020"

With a 16:1 twist you can go to a bit longer bullet.

She is deadly on chickens at 220 yards.

I just finish putting a new barrel on my original Hepburn. Chambered it for .38-40 Remington just to be difficult. I'll be shooting black powder and fixed ammo for now. I took it out and fire-formed some brass and it seems to want to shoot. I'll post my result as I go along.

Steven Durren

I have a .38-40 Remington reamer. The neck measures .402". I still had to ream the necks of the Winchester brass I used to fit .375" bullets. 

I'll be casting more bullets this weekend and I should have a report later next week.

Steven Durren