this 14.5 Its for plinking. (no, thats a joke) But there are bigger guns then this
This rifle is built around 20 mm hispano cartridge. AAA.
en.wikipedia.org
However, 14.5 can be well used.
During siege of Sarajevo, they found one old russian antitank rifle, I think Simonov. cal 14.5x114.
This rifle was partly effective against the tanks at early stage of ww2, but when the armor improved, it wasnt so, and some were obviously delivered to partisans during ww2. Production stopped at 1945.
So, one remained in Sarajevo museum.
During the siege, they took it out of museum, found some ammo for it (or smuggled some ammo), and succefuly used against serbian bunkers and military installations.
There is one unconfirmed story of sarajveo big caliber sniper duel, when serbian 50 BMG machine gun, was shooting rapid fire at sniper at approximate location of sarajavo shooter in one of Sarajevo buildings. 50 BMG was crushing the floor and walls above and around the sarajevo shooter, and he was just below, in dust and rubbles, and and in heat of moment managed to take good aim with this simonov 14,5, and destoreyed 50 bmg, and its handler with one shot. A duel between 14,5 and 50 bmg.
(if it was american conflict, I am sure this story would be made in Hollywood block buster movie, of the type enemy at the gates...)