I have a Browning B78 in .243, as a test cycle action to full #### then pull trigger with thumb on hammer and lower hammer to fire. Slowly pull back on the hammer and should be hit safety “1/2” #### about 1/4 or 1/8th from full fire. Once you feel where the safety position is you can lower hammer to it from full ####, by pulling trigger (thumb on hammer). Suggest you do this a few times with out a cartridge in the chamber....
You could also go the Winchester.com (I think) and look up serial number to see manufacture date, then research to see if your model was equipped with 1/2 #### safety.
Cheers,