first, make sure the rifle is unloaded.

rack the bolt into battery, cocking the hammer. pull trigger. CAREFULLY observe from the side that the hammer is contacting ONLY the firing pin and NOT the rear of the bolt or carrier. if the hammer is giving you and incorrect hit on the firing pin...junk it and buy a redstararms fire control group that is made SPECIFICALLY for your sar3.

if you are getting a good firing pin strike, you will need:

brake or carb cleaner.
air compressor with air nozzle/gun.

clean the firing pin channel out.

it may be required that you have to detail strip the bolt...but try aerosols and compressed air first.

if you have to detail strip th bolt head, remove the extractor pivot pin first (careful! the extractor claw is spring loaded)...then drive out the firing pin's retainer pin and withdraw the firing pin to the rear. clean passage way.

And make sure the fcg is not comign adrift somewhere causing the hammer to hit less hard as the spring shifts.

$10 1" rubber extension (AK/SKS same pad) at Tapco and a red dot will fix your fit issues :)

Make sure it hass a hammer of the proper geometry.

An SAR-3 requires a special hammer that only Redstar Arms offers.