The Taurus Rilfe is a unique hunting rifle, originally owned by the Zodiac Clan member Taurus . The Rifle is heavily modified and improved, compared to a regular hunting rifle. The weapon was first used by Taurus when he and his partners, The Gemini Twins were pursuing Blackjack in Flankfurt.
The Zodiacs were hunting Blackjack in a bid to claim the bounty on her head and to recover her Pipbuck, which had the program EC-1101 on it. Taurus eventually turned the weapon on Deus the Reaper when he attacked the Zodiacs, the weapon proved capable of piercing Deus's armoured chasis but provided little more than an annoyance for the Reaper.
After Deus and the Zodiac's were killed, P-21 began looting their corpses. Blackjack with her fine appreciation of guns, recovered the Taurus Rifle since it's original owner was now dead and made it a part of her growing arsenal of weapons.
Blackjack frequently uses the scope attached to the Taurus Rifle as a means of spying on ponies from a distance, like a telescope.
The Rifle is given to Bluebelle, Taurus's sister, by Blackjack, so she would have something belonging to him to remember him by.
The weapon is well maintained and cared for. It has a wooden grip with a bull's head branded on to it, like the Zodiac sign Taurus. The weapon has a scope attached to the top and is heavily modified compared to regular hunting rifles. This likely allows it to fire the armour piercing rounds it can use.