That's a pretty slick idea!

What works for me is this. I made a flat mandrel to replace a shell holder. Then made a simple die by boring a piece of 7/8-14 threaded rod for an easy slip fit of the case. An acorn is set on the mandrel with a case started over it. The ram is raised and the rim stops against the bottom of the die and the acorn is seated flush. This does not seem to stress the rim. In fact, it straightens it if any deformation is present from previous firing pin hits. 

For other rimfires (38, 41, 44 etc) I can use the same mandrel, but often find another die that works  for stopping on the rim.

Yeah, I can see how that would be a problem 

Little factoid I noticed in a Stevens catalogue a day or two ago:

Touting how the Model 44's takedown feature gives the possibility of having multiple barrels, they state in black and white that .22 and .25 rimfire barrels use the same breechblock.

We knew that of course, but now we know that it was intentional.

This and a couple other threads inspired me to get out again. Bored out the seating stem to keep from deforming the bullet nose when seating. Changed the process of necking up the 17 WSM brass and a couple other small things to get more concentric brass. 

It’s all starting to come together. 

First target was before using the new seating stem. Second target was with new stem, third after changing bullet diameter. Sizing the bullet to .257 is getting a cleaner release and probably reducing some deformation of the bullet when seating. 

7 grains of 4227 and a .030” wad. 70 grain bullet. Last 5 shots were just under 3/4” at 50 yards, iron sights.

uscra112 wrote on Mar 5^th, 2023 at 11:05pm:

Keeps the base from looking like it hit with buckshot. A lot less deformation.

44 1/2, front I believe is an original or at least of the era, rear sight is an MVA Vernier.

Anticipating warmer weather, I started gathering up stuff for a .25 Stevens testing session.  Found I have EIGHT shootable rifles in .25 Stevens!  Good Grief!  Not only that, but I found a 44 in .32-40 that I didn't even know I had.   

Also learned something about chambering.  I had Dave Manson make me a reamer, and have done one newly relined barrel with  it.  Now, as it happens I have a few converted Hornet cases that are slightly bulged from the expanding plug going too deep. These will go into my new chamber, but I have a 44 with a 99.9% mint barrel. and darned if they don't hang up in that!  Actual OEM chamber was tighter than what I thought would be "tight" dimensions!