Victorian silver gun pendant

This gun pendant is really big, it measures about 7cm in total and its heavy too.
I bought it together with the memorial cross from 1917 I posted yesterday and a 'matching' victorian shovel pendant on a flea market for about a buck.
One corner of the handle has a crack, but I dont mind. I think its made of horn.
It has some markings: S or 5 AR 925
Can anyone tell me its origin and when it was made?
Thanks a lot!