Hello all. I am trying to remove the upper half of the gas block on my Mini-14 in order to install a foreward mounted weaver rail in its place. The entire process simply requires the removal of 4 screws on the underside of the barrel (see pic's). However, the problem is that these screws are absolutely unwilling to turn, no matter how much "elbow grease" I apply. I have the correct allen key, and have tried lubricating the thread (I can access the thread from the top, bottom, and side), but with no luck. Is there something I am missing here? Thanks for any help you can provide!