I copied this from 6mmbr. The site has alot of info on the .20 calibur. Here is the link for the actual story..
http://www.6mmbr.com/gunweek061.html
Comparing the 20 Practical and 20 Tactical
Kevin tells us: "The 20 Practical and the 20 Tactical are almost identical cartridges. There are only slight differences in case Outside Diameter, shoulder angle, and case body length. The neck length on the 20 Tactical is a bit longer, but there is still plenty of neck on the 20 Practical to grip the popular bullets, such as the 32gr V-Max. Here are some specs:
Cartridge__________________20 Tactical____20 Practical
Bolt face to shoulder___________1.5232"______1.5778"
Shoulder O.D._________________.360________.3553
Shoulder Angle_________________30°__________23°
Total length___________________1.755"________1.760"
Both the 20 Tactical and the 20 Practical are fine .20 caliber cartridges. At present, the 20 Tactical is the more popular of the two because it has had more publicity. However, my favorite would be the 20 Practical. Warren's 20 Practical gives the SAME performance as the 20 Tactical without fire-forming, or having to buy expensive forming dies. So with the 20 Practical you do less work, you shell out a lot less money, yet you give up nothing in performance. What's not to like? To create 20 Practical cases, just buy a .223 Rem Redding Type "S" Bushing Die set with a .230 or .228 bushing and have fun with this great little cartridge."