Has to be some type of aperature sight.
I can't see how it would mount exactly, maybe in the rear claw base.

It is very similar to my Manton.
Don't underestimate the power of the 22 Savage HP! In a different class than the 22 Hornet.

The online translator I use doesn't give me much...

Double can of George Gibbs, Bristol. Made probably about 1930 (the precise date is to be found out no more, because all documents of the manufacturer from this time were destroyed). The caliber 5,6x52R (Savage) is original (see stamp). The fastener is also steady with taken Vorderschaft. With ejectors. Run length 53.5 cms, the runs are reflecting-shining. Original shaft (length 36.5 cms up to the front deduction) of wood grained lively and nicely and with engraved Schaftkappe from metal. In the gun clutch lift-up lid. Very good, not measured engravings. Mounted with bald 2 7 fold from steel with double Absehenverstellung (paragraph 1) and with soldered wheel assembly. Total weight with ZF approx. 3.8 kg. Total length 95 cms. In addition, still with original auxiliary optics (with manufacturer's name engraved). In the original leather suitcase, this it was adapted merely for the ZF and his belts are renewed. It concerns all together around führige and very well-preserved weapon with only low use tracks.