Rail alignment fixture to install the lower bolt guide rails in 1mm receivers. The rails clamp inside the fixture which inserts into the trunnion to keep the rails even with the trunnion.
The main body of the fixture goes in the receiver first and is bolted to the receiver and trunnion. Then the rails are clamped in the front with the screw and clamp. Be sure to push the rails in so they touch the back of the front trunnion. The rear most section of the rails need to be leveled with the top rail from front to back by measuring down from the top rail then c-clamped in place. Then a weld on the front and rear of each rail is made to hold them in place so the fixture can be removed to finish all welds on the rails.