Nothing can cause a good group to go sideways at the range like a loose or cracked gas cylinder screw. Sometimes the interior of the screw can also become fouled which prevents the spring loaded valve from closing completely. In all cases the end result is an inconsistent supply of gas which will affect both accuracy and functionality.
The interior face of screws should be checked for cracks. If they exist the screw should be discarded. Screws can also be cleaned to ensure that the valve will fully close. You can buy a little whiffticker tool to depress and hold the valve open while you clean the interior with a spray cleaner and brush. Alternatively, you can just clamp a punch in the vise and then press the valve face against the punch to open up the interior of the screw for cleaning.
Folks should make sure that their range box includes either a Garand combo tool, an appropriate size screwdriver or a 1/4 inch socket drive to check and tighten the screw periodically while shooting. One good workaround which eliminates any concerns about a cracked interior face or a sticky/fouled valve is to use an Italian BM59 gas cylinder screw. These are solid with no valve and also have an Allen type socket in the front face for installing/removing the screw. You still need to have an Allen wrench in the range box to check and tighten these periodically. The BM59 screws aren't "collector correct" for a Garand, but work well for a shooter. Old time match shooters used to prefer the early pattern solid gas cyl screws which did not include a valve for use with a grenade launcher.
The interior face of screws should be checked for cracks. If they exist the screw should be discarded. Screws can also be cleaned to ensure that the valve will fully close. You can buy a little whiffticker tool to depress and hold the valve open while you clean the interior with a spray cleaner and brush. Alternatively, you can just clamp a punch in the vise and then press the valve face against the punch to open up the interior of the screw for cleaning.
Folks should make sure that their range box includes either a Garand combo tool, an appropriate size screwdriver or a 1/4 inch socket drive to check and tighten the screw periodically while shooting. One good workaround which eliminates any concerns about a cracked interior face or a sticky/fouled valve is to use an Italian BM59 gas cylinder screw. These are solid with no valve and also have an Allen type socket in the front face for installing/removing the screw. You still need to have an Allen wrench in the range box to check and tighten these periodically. The BM59 screws aren't "collector correct" for a Garand, but work well for a shooter. Old time match shooters used to prefer the early pattern solid gas cyl screws which did not include a valve for use with a grenade launcher.
