I just slugged the bore of one of the H&H 38-55 "Target" models.
The bore dia. was a very uniform drag fit on a .375 jacketed bullet.
Unfortunately the groove diameter is .380 so the grooves are very shallow. Is this thing going to shoot? And...yes the chamber is too small to permit chambering with a bullet larger than .379 without opening the chamber or turning the case "necks".
Anyone know where I can scare up some .381 or .382 cast bullets? I don't want to buy a custom mold if it is not going to shoot.

I had one of those and found that in order to chamber the rounds with .380" diameter bullets I had to run loaded rounds into the sizing die about 1/8". That sized down the top band of the bullet and case to fit in the chamber.
I sold the HR and bought a C. Sharps 1885 with a .376" groove diameter. I use .377" bullets in it with no problems.

Hello Leo
My chamber is the same way. The last 3/16 requires a hard thumb push with a .379 bullet.

My 94 Win. has a large groove diam. .381 and the loads would not chamber also. So I rented a reamer ( I think it was JGS ) it only took about 4 turns on the reamer to clean it up. Bernie

Hello ireload2...I am in the same boat as you except my groove is even larger at .381+. Same thing on a Marlin CB in 38-55. If you rent a reamer please let me know who you got it from and how it turned out. Thanks

I guess I will be looking for a reamer.
I shot the thing at 50 yards with .379 bullets and got groups running about 1.25" to 1.5" with 3 out of 5 different loads.
Sounds like we could rent one reamer and send it on a merry trip around the continent!!!

Bernie
I have a .375 Marlin that checks .3778 groove diameter.