P08 wrote on Aug 22^nd, 2022 at 9:19pm:


I'd use a .377 sizing die, good way to do that is a Lee push through:
(You need to Login or Register to view media files and links)


Then, you may have to custom size the brass to work, a Lyman M expansion die in the correct diameter is the way to go:

(You need to Login or Register to view media files and links)

Might have to have a custom expander plug made up for the Lyman, not sure what size the factory one is.

Did you get to shoot the rifle today?  How did it do?

I shoot my 38-55 similarly, with slip fit bullets that slide into the fired case with no resizing.  I drop my powder charge, fill the case to the top with wheat bran that is shredded to a fluffy powder in my spice grinder, put a tight fitting wad on top and then seat the bullet to the depth where it fully seats into the throat of the rifle.  The bran holds the powder in place and gives a lot more uniform velocity.  I started out using Puf-lon, and when it became unavailable, switched to bran.  more labor, cheaper, and seems to work just as well.   

You're fortunate if a bullet .0015" over groove slip fits into your fired casings.  I had a custom reamer and custom bullet mold made to make it happen in mine.

ssdave

Years ago I was using SuperGrex shot  buffer to do something similar but in some cases it left goo in the throat. Are You are doing this with smokeless loads and your ground up bran correct?  In my Ruger  cap and ball revolver target loads  I use cream of wheat for filler until I made longer loading rods so I didn't have to do this step.
That's a neat idea, Thanks for posting that.

Well I  ran short of the .375 JSP bullets. I did however come up with a way to fix my issue. I took the leftover brass that I had sized too small and seated a .375 bullet. Then pulled the bullet. Loaded a .378 lead bullet and even though there is a slight bulge, the round chambers. This will allow me to blow the case out. Then I never size the brass again!