What, specifically, do you want to know? There are a TON of teams out there. Just for the federal teams alone, there are bothy regional and national teams in some agencies.
In all instances, you will need to get on with a specific agency and prove yourself on the job before you can request consideration for a tactical team. The opportunities of each team can vary greatly and it really is going to depend on what agency you are considering.
You would be a fool to pick an agency just for the tactical team. For example, if you can get hired by the FBI and went there ONLY because you want to be HRT, you will be very disappointed. The Bureau is anything but
tactical and even IF you can get on HRT, you will not be there your entire career... and what you do in the field offices is a far cry from what you would do on HRT.
I can tell you, first-hand, that the FAST team guys are a great bunch of guys. They are extremely professional, well-trained and high-speed. I did a lot of work with these guys in Afghanistan.
Now, HRT on the other hand, is not so generous. I am hoping that it was just a fluke, but these guys would not go out over the wire in Iraq when there was a genuine need and urgency. They would preferred to leave guys understaffed in a hot environment than go out there and back a fellow agency up. I know that it was not the guys on the ground as much as the administration, but still.
FWIW, I did a significant time on a team for a "major agency" that you apparently did not consider. Look into the U.S. Marshals Special Operations Group (SOG). If you can get hired by us AND Pass our selection, you will get a chance to participate in a huge variety of high-threat missions. You will get to do everything from 6 month tours in the mideast to take-downs of militia ranches. You will get to work on supporting DOD programs that don't exist as well as dealing with security of the domestic terrorist prosecutions. When the AG didn't know who to give an operation to, they gave it to us. You will do everything.
...BUT, the first thing you need to do is get hired.
We bring evil things to evil people, kicking in a door near you!
."In theory, there is no difference between theory and practice. But,
in practice, there is."
- Jan L.A. van de Snepscheut
"The difference between 'involvement' and 'commitment' is like
an eggs-and-ham breakfast: the chicken was 'involved' - the pig
was'committed'."
-unknown
Working on a PhD in CQB one doorway at a time.
When the wolf attacks, he will find not all who run with the flock are sheep!