*** I'm not a gunsmith nor I portray to be one, I'm just an average Joe with nothing else better to do with my time at home.... this is what I found and it's only my opinion from my own experiments and you should consult with a qualified and competent gunsmith****
Rifle- My sons rifle a Winchester 70 270 weatherby mag with a timney trigger conversion.
Problem- trigger is stuck on fire and won't engage with in cocked or fired position.
Observation- when cocked I noticed the firing pin (shroud part that sticks out the back when cocked) is shallower than my other rifles WITH factory triggers and exactly the same as one with a timney trigger that I bought long ago. Not by much but noticeable.
My guess- is that with the trigger conversion the firing pin rests on the sear much deeper than the factory firing pin, thus having the firing pin moved slightly forward preventing the 3 way safety from working as it should, as it operates with almost zero play. It would be a disaster if there was wiggle room, the trigger was accidentally hit while on safety disengaging the sear and come to rest on the safety and firing when the safety is switched off because it's already off the sear.
The fix- this is my "backyard" fix and most people will cringe but it works!!!! So I took the bolt apart and took off the spring. Took out the firing pin and filed the angled notch VERY LITTLE AT A TIME where the safety post rotates. After around 20 or so times assembling, disassembling and testing I finally got to make it work!!!! I tried to bump fire, whack it with a rubber mallet and it didn't fire until I switched the safety off and pulled the trigger.
Regrets- I should had taken measurements before and after so I could keep as reference so I could change triggers in my other rifles and see if it's consistent or backs up my theory. Anyways it now works and now I will feel safer when my son uses his rifle because it's a hammer!!!
I hope this helps.... good luck!!