Danny, this is the heart of the matter. The truth is you
want to full length size the brass each firing to maintain consistent accuracy. I'm not aware of
anyone shooting a 30BR that doesn't full length size after each firing.
Stay away from any sort of bushing/bump lash-up die that doesn't size the entire cases (Forster or Hornady).
Fortunately, the 'map' for 30BR dies has been well drawn for may years. You only need to follow it to get a good working die.
Dies like the Redding Type 'S' full length bushing die (#71524), the Wilson full length bushing die (#FLD30BR) or the Harrell's full length bushing dies will all do the 3 things you need a die to do:
1- Full length size the case
2- Properly move the shoulder back
3- Control the neck sizing with a bushing that floats
The trick, of course, is to get a die that works with your chamber dimensions. That brings us back to your chamber reamer, what the chamber measures and more ,....what the fired cases measure.
This is where Harrell's shines as they offer different dies with different internal dimensions to match what your fired brass measures. They will also swap dies for another one with more/less sizing if you want something different. Their 'default' 30BR die if they don't have fired cases to check is their 2 or 2.5, which isn't a bad place to start. I like a little more aggressive sizing so for me, a 3 works. If the back end of the chamber is fairly large, the 3 might be too much.
If you have a Redding Body Die for the BR cases that sizes your brass the way you like, they can be converted to a bushing die by Jim Carstenson at JLC Precision. The Redding Body die for a 30BR is #75524. The only difference between it and the Body Die for any other BR cases is the diameter of the neck opening. So if you have a Redding 22BR or 6BR Body Die, they are perfect for modifying to a bushing die. The internal dimensions of the Redding Body Dies are the same as the full length bushing or non-bushing versions for the same cartridge so if a Redding Body Die sizes correctly, you can confidently order a F.L. Bushing Die of the same 'cartridge family' and it will size exactly the same. I have several Redding Body Dies that have been converted to bushing dies by Jim Carstenson.
The Wilson full length bushing die sizes exactly the same amount as the Redding 30BR F.L. Bushing Die.
So you really have three good choices in a full length bushing die. Are there any road blocks in sending in sending fired empty cases from Canada to the U.S.for Harrell's to measure?
Good shootin' -Al