Now those are some cool custom tools!
Mine is much less involved. I put a Glock disassembly tool thru the drainage hole to retain the spring. Remove the c clip with snap ring pliers, then unscrew the stock retainer plug with the Weaver bit. With the Glock tool in place, the spring will only extend a few inches past the end of the extension. I then cover the end with a rag and pull the Glock tool to set the grease snake free. The spring tension isn’t too crazy. Then the plunger dumps out with gravity.
Reassembly is pretty easy. I put the shotgun upside down in the vice so gravity is on my side. Drop the plunger in, then start feeding the spring in. I hold the bottom of the receiver extension with my left hand and feed a few inches of spring in at a time. I then grasp the newly compressed section of spring with my left hand thumb and pointer finger. Repeat until it’s flush with the receiver extension. Insert the Glock tool thru the drainage hole and only a couple inches of spring will extend out the end. It’s then easily compressed with the stock retainer plug and screwed into depth. Remove the Glock tool from the drainage hole and release the spring. Reinstall the c-clip with snap ring pliers.