Does anyone Know what thread size the barrel stud is. I recently acquired a model 99 and a previous owner installed a sling stud in place of the fore end screw. He cut the stud shank too short and it is only hanging on by about 2 threads. Also I suspect the threads on the stud are not quite right and have damaged the first threads in the barrel stud. I would like to re-tap the threads and get the proper screw.