I have several Lee 3-die sets (357 mag, 44 mag). In those, I use pistol NOE expander plugs in the middle die and it works great.
I bought RCBS steel 3-die set for 45-70 just to try a different brand. I notice though that an NOE expander plug will not fit in this it appears, as the expander is very tall, and threaded.
What would I do in this case?
I'm using cast boolits (.458 diameter), and both plugs I got were .002 and .003 neck tension so I could try both.