as kudue told me it looks that this mannlicher is also made from George Gibbs, Bristol.
the "B" prefix before the serial number seems to be a serious indication for this maker.

http://forums.nitroexpress.com/showflat.php?Cat=0&Number=167792&an=0&page=2#Post167792

front sight and rear sight are very uncommon. I take a close look to the sights and would say that base for the rear sight and base with front sight are old or original. the rear sight itself is maybe post war german and have a blueing the other parts are missing.
Axel knowing this front sight only from rook rifle's but the old Jefferey's catalog have it

if the rear base is realy the original this Gibbs mannlicher never had an express sight. Axel say it had only folding sight's when the rifle came with a additional lyman sight from Gibbs. something like that?

the hole rifle was scrub with file and sandpaper outside. heaven know's why! I have startet to polish this again.

it seems that the scope mount is an early Holland&Holland design. I did not worry about making two new feets but would like to know how the original have look. maybe I take a realy old scope model from before the great war for this rifle. will set it on the left side so the clip can be loade without problems.

patience is needed till it looks like that again, and a lyman sight also