Measure your trigger pull.
Remove the barrelled action from the stock.
Measure the trigger pull again.
Any difference? If so, you have interference from the stock.
Remove any offending wood & try again.
Next, spray everything down, including your bolt, with brake cleaner.
Then check if there are any burrs on the sear or anything interfering with the trigger's release.
Do this with a fired case in the chamber to prevent damage to the firing pin & chamber.
When all else fails, what I've done is replace the trigger spring with a pen spring.
I've also added a spring steel [banding strap] collar under the trigger guard, with a rectangular cut-out to act as a trigger stop [go slow; you can always remove more metal, but if you remove too much, it's back to square one!].
Forgot to add, if it no longer a 2 stage trigger [this was done to simulate the 2 stage S.M.L.E. trigger pull], then someone's messed with it.
Just my $0.02 Cdn.