Installing a choke tube is a fairly simple process, but there are a few things you need to keep in mind. First, make sure the gun is unloaded and clear of all ammunition. Next, locate the choke tube threads at the end of the barrel. Slowly screw the choke tube into the barrel until it is snug, but do not over-tighten as this can damage the threads. Finally, reassemble the gun and test-fire to make sure everything is working correctly.