This experimental G. Sturrock patent breechloading centerfire conversion rifle uses a breechblock that opens in the style of a trapdoor. By grabbing a top mounted lever on the breechblock, the breechblock unlocks at the rear which allows it to lift upwards through rotation on a front mounted hinge attached to the top of the breech face, allowing extraction through the use of the sliding breech face that is able to be manually pulled backwards. The top of the breechblock is marked "STURROCK'S.PATENT./CENTRALFIRE" in reference to G. Sturrock's British patent number 916 dated March 29th, 1866. Fixed front and graduated ladder rear sight. "25" with London Crown proofs marked at the left of the breech end of the barrel below the breechblock, and "24" with London Crown proofs marked ahead of the breech in reference to a rechambering from .577 to .58 caliber. A breechloading rifle such as this was very likely intended for military trials.