I have a BSA rifle - think its a 'Monarch' but there's nothing on it to give a clue.
To be honest there's not all that much of the orginal rifle left - it has been re-stocked at some point long since with a very nice piece of walnut and I rebarreled it from the orginal 7x57 to 7-08 a couple of years ago with a Border cut rifled tube cos it never shot too well and I suspected the thing was gone. It now shoots just fine.
The firing pin spring has never seemed to have all that much grunt and once failed to ignite a round. It just sounds and feels weak - its undoubtedly the same age as the rifle - 40 - 50??
I have had the spring out and checked it - but where can I get a new one? Does anyone know anything else which would fit to give more of a ping? I did have a quick google but without anything positive back.