The 204 Ruger does not use the .223 as the parent case, it's case is from the 222 mag.
20 Pratical= .223 case sized down
20 Tactical= .223 case sized down
I recently had a quest to get a 20 cal gun and wanted the 20 Pratical, I gave up when nobody around here had a reamer or had ever done one. I now have a 204 Ruger AR-15. It shoots as good as any factory bolt gun I have if not better.
I have used Hornady, R-P, and Winchester Brass. They charge 23-25 for 50 Hornady cases, and 25-30 for 100 R-P or Winchester cases. The loads worked in the Hornady and R-P,and Winchester are able to work in each other.
R-10X and N-140 for the 32 Grain V-Max
R-10X for the 39 Sierra and 40 V-max.
I used the Dan Newberry Method. Optimal Charge Weight
http://www.optimalchargeweight.embarqspace.com/
I settled on a "Mild" load, I have shot some brass 3-4 times, and never had to trim for length yet.