The multi gasket kit I got off fleabay has two base gaskets. Both would seem to fit, but are of different thicknesses. One is quite thin, made of straight, plain gasket paper, the other one is more like cared, blue finish and slightly larger on the outside diameter. Is this the correct one for a square barrel ? does it matter, or is it another one of those "Oh my GOD, don't whatever you do fit the.." moments ?