hi mapsjanhere,
sorry, but your question is a little bit like "I have a Ford with black interior tim - value?". It simply can't be answered.
The caliber probably is 11.15 x 65 R as this was a very popular caliber for drillings at the the end of 19th/beginning of 20th century.
Value will depend on model and condition. If it is a model with outer hammers, value will be low. Only if it's a sidelock model with cocking/decocking lever for the rifle barrel, the value will reach a higher level.
Photos would help to tell more.
Regards
Martin