About 10 years or so ago Winchester came out with the Black Talon.  So called due to the black coating of the bullet (lubox or lubealloy)designed to reduce friction and heat buildup in the barrel as well at the bullets very novel expansion qualities.  Instead of simply expanding, the bullet "peeled" to create what were known as "talons" which did a very respectable job of acting like a food processor in the wound track.
The bullet worked great.  It worked even better in the mind of Congress and the public and Winchester pulled them off the market.
Rather than going the way of other "evil" products such as the Lawn Dart, Winchester took the coating off, made the bullet an even more efficient food processor and dubbed it the SXT (Supreme Expansion Technology).
Winchester reintroduced this ammo as the Ranger T series and markets it only to LEO and Military.  You wont find this at Walley World.
Ranger T's have greater performance and stopping power that the original Talons.  This is some of the most extensively tested ammo ever developed.  Winchester actively tries to keep Rangers only in the hands of LEO/Mil and out of the hands of civilian shooters.   It's Winchesters rule not a law so its perfectly legal to own and use (state and local silliness aside). 
There is no guarantee that Rangers will be available in the future and since history repeats itself, there is every reason to predict they will not.

Demand for this ammo is far out pacing supply - in other words it's damn hard to get reliably.

Original BT's are still available at outrageous prices and about 10 years worth of dust.