How do you install a plug in a browning a-5?

Answer 1

First, pull the Breach bolt rearward and lock open. Remove the magazine cap at the end of the forearm. Pull the forearm forward and off while keeping pressure down on the barrel. Carefully hold the barrel as it slides up and off the magazine tube. Depending on the age of the gun, the end of the magazine tube usually has a Magazine Spring Retainer that is inside the magazine tube. Slide the plug into the spring and push the spring back into the tube. You may need to tap the end of the plug to make it level with the rim of the tupe. Reassemble the band on the end of the tube and reassemble the gun.

Check the link at the bottom of the page and go to page 7 of the Auto-5 manual for more detail.