of silencers was a stroke of genius, A frined of mine, John R, came up with that one. It's very easy to create, serves as a pressure release valve if something is wrong inside of the can, adds almost no weight to the can, only uses about 3/16" of space inside of the can. Threading a can's tube and making threaded end plugs is a royal pita. So weld in the rear endplug and use the snapring idea as the front endplug. Works just fine. When you're working with a can that features a sleeve tube, make the front washer (the one between the tubes) about 1/2" wide, so that if your lathe bit breaks thru the internal tube, there will still be no gas leak.