I've never seen one with screws like that, it may be they were replaced at some time. It looks like the spring wire is handmade also, that's your trigger poundage. I have a factory wire if you want it. It will increase the trigger pull weight. Search 3 screw trigger for adjustment information, it may just need adjusting. Another thing, the threaded piece that the wire end is in, can be adjusted, just take a flat screw driver and turn it clockwise to increase trigger pull. What year is the rifle? It might just be an older design.