I have a 1903a3 and the action screws need to be replaced. I also need to clean up the threads in the action but am having problems finding the right thread pitch. The screws that were in it are 1/4" and the new bolts have the same TPI but they are not 20 or 28 TPI. Does anyone have a reference manual which shows what the threads are suppose to be? The screws are very close to a metric 1.0 if that helps. Thanks in advance.