My latest build was a late Valley of Virginia rifle with double set triggers. I used the L&R because the bar for the front trigger was high enough to allow for adjustment of a good pull. This trigger also has an adjustment screw to limit the travel of the rear trigger main spring. Sounds like a good idea, and even if it is a socket head screw it is small enough to not be noticed. The problem is that every time the spring hits the screw it puts a strain on the threads in the direction to unscrew the adjustment. I didn't notice this until the lock would no longer stay in the full cock notch of the tumbler. At first I though that something in the lock had broken, but that was not the case. The rear trigger had gradually worked upward until it was touching the sear bar and keeping the sear from seating fully in the full cock notch. Not so much to keep the lock from being cocked, but enough to let the lock fire unexpectedly; a rather startling and dangerous situation.
I have since staked the trigger plate adjacent to the screw and put a drop of stock finish on the threads, but haven't used it enough to know if this will keep the adjustment. In the meantime I thought I would share the experience and give others a heads up.