Well I have to come clean and say that I guess I am intimidated by using a bushing die set-up.
Never seen one used so I am completely ignorant on the subject. Always used 2 die rcbs sets.
In searching the 20 prac. out I think I've seen 6 or 7 different size bushings. How the heck do I know where to start and what bushings to use. Some do it with one bushing some with 2. Confusing to me! HaHa
Never seen a specific 20P die set.
Reloads, for LC or other thinner neck wall brass most of us end up using .226"-.228" bushings (or a cut down or shimmed 204R collet die or universal 20 cal neck die), thicker stuff like PPU, Lapua etc. .229"-.231" (or a cut down or shimmed 204R collet die or universal 20 cal neck die). Depends on your preference. Rule of thumb I use is loaded diameter - .001" to start (assuming brass is annealed/new). Loaded diameter - .002" can cause excessive seating force and case distortion (mushroom at shoulder) if the brass is freshly annealed so pay attention to your situation.
For forming l also strongly prefer a multistep method, its almost mandatory with fired brass as the necks can be up to .252" or so OD, even larger in some instances. New 223 brass tends to ship at about .243" neck OD and if there is a decent radius or chamfer at the bushing mouth it can be done in one step no problems. Another option for 2 step method on fired brass is to use a 223 FL or neck die with the expander removed, these generally get you to .241"ish (the expander will put it at .243"ish) then final size. Recommend giving the neck OD a light chamfer before trying to neck down, and trim 'em after if LC they can be rather long to start (1.765") even new, and 1.770+" if milsurp once fired. Chamber length is usually 1.770" unless you have a custom reamer.
Forster also makes a 223 bushing die, it requires the same conversion as a Redding (17-20 cal decap setup, with or without the 20 cal expander), the parts are generally cheaper than Redding especially the bushings. I converted the Forster 223 micrometer seater to 20 cal and don't like it- the seating stem is VERY thin at the mouth and distorts immediately then becomes useless. Some of the 20 cal seaters aren't worth a crap and turn those spitzers into spire points (Forster again) because they seat very near the hollow and thin section near the bullet tip. Sometimes the 223 seater stems work better, but the Forster micrometer seater you have no choice have to convert both body and stem to 20 cal.
The Hornady universal 20 cal seater works fine and is cheap.
Reviews of all the 20P dies I've used-
204R Lee collet die (cut down approx. .075" at base of chamber)- works good until a FL size is needed, good for bolt guns and mixed headstamp brass.
Hornady 20 cal universal seater- works as well as any. Has roll crimp function if desired.
Redding 223 type S bushing die (NS or FL)- works fine, the gold standard.
Redding 223 seater- works fine, usually no need to change seater stem.
Forster 223 bushing sizer die- works well (after 20 cal decap conversion)
Forster 223 micrometer seater converted to 20 cal- not recommended.
If you already have 223 dies you may have a lot of it covered already. What 223 dies do you have now?
