Yep, it's like shooting in the dark unless the guns were in our hands, but I wil go ahead and take a stab at rifle #1. The problem is probably associated with your front trigger blade. The blade could be contacting wood before it makes contact with the sear bar, thus stopping the travel. Or, perhaps the blade is not high enough, so that it never touches the sear bar as it reaches its travel limit. If that's the case, someone may have filed it off to low. Or, maybe you don't even have a front trigger blade. Some set triggers are set up that way, but I really doubt you'll find that with a production rifle.
Remove the lock but not the triggers. Pull the front trigger back to check if the trigger blade shows in the hole for the sear bar. If not, You'll need to decide whether the wood is stopping it, or there just isn't enough travel to get into that recess.
If you get to this point, why don't you come back to this post and someone can help from there. There are some fixes, but I don't want to write them all down until you diagnose the problem. Good luck. Bill