I installed a Timney trigger in a old remington 721. I had to do some work to the stock to get the trigger to fit. The trigger now has plenty of room and when I set the action in the stock it works perfectly but when I tighten the action screws the firing pin will not stay engaged. If I lift the bold handle the firing pin moves to the cocked position but when I put the bold handle down the firing pin won't stay engage. I can tighten the rear tang screw and leave the others loose and it works properly but as soon as I tighten any of the other action screws it won't stay engaged. Or I can have all the action screws in but loose and it works properly. Can the action be flexing enough that it's messing with it?