weld in the rear endplug, having forgotten to first deburr the vent holes in the rear 4-5" of the inside tube. Those burrs make it HELL to insert and remove the blast diffuser. If you do forget, you can always make an extention-rod for a 3-pronged hone, sold for polishing out brake cylinders on cars, and use a hand held electric drill to spin the hone inside the tube, knocking off said burrs. This will probably tear up the $10 (or so) hone, tho, and you'll need a lathe to make the extention for the hone.