Have played around with a couple. Good round when set up for heavier 20 cal pills. It is reported to outperform the 204 Ruger but in all honesty, I do not see how this is possible without extremely high pressures as it is nearly identical in case capacity, even a slight edge for the 204 Ruger.
I have been thinking about having a 20 BR reamer made up. This with the heavy +45 gr bullets would werve well for a long range rig. A 50 gr bullet would really make this little round reach out there.
Back to your question though, the 20 Tac is a great round, but it is what it is, basically another version of the 204, an earlier version though and as it is based on the 223 Rem case a much better design as well as brass is in endless supply.
Remember though that if the 20 Tac produces noticable velocity increases over the 204 Ruger, it is a result of higher chamber pressures as the two are nearly identical in case capacity.
Kirby Allen(50)