Kegging in a beer keg

Has anyone converted a “regular” beer keg into a refillable home brew keg? It seems like it would be a fairly easy conversion. I just picked up a 15.5 gal AB keg to make a keggle with and the more I look at it the more do-able this seems. Take out the snap ring and rotate the center “valve” until the tabs line up and out it comes which leaves a hole large enough to poor in 10-15 gallons of home brew without to much difficulty. It looks like all you would really need to do is add a ball/pin lock for CO2 and maybe a pressure relief valve and then it would be good to go. Anyone ever tried this???

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It’s possible. The issue is can you properly clean the keg.