Tapered bore hunting rifles?

[Minihuntur]

I recently read that Walter Gerlich (inventor of the German super high velocity tapered bore cannons of WWII) designed some tapered bore hunting rifles in conjunction with a gunmaker called Halbe. These used a barrel that started at the bullet diameter and tapered to a smaller diameter at the muzzle. The bullets had soft flanges on the side that would collapse as the bullet passed through the bore causing great pressure to build up behind the projectile resulting in a higher muzzle velocity. His 28mm cannons were capable of pushing a 4.62oz shell at almost 4600FPS! His hunting rifles were marketed under the name of Hal-Ger. Does anybody know any other info about these guns or possibly where I could get one
Minihuntur