I bought a pair of ball lock QD's along with a picinic tapper and some hose of Amazon a couple weeks ago and I'm just now getting to the point where I need to set them up (fortunately no beer ready for the keg yet). When I tried to put the QD's on the keg both of them were too tight to go on. I took my handy calipers and started measuring and I found that the QD's have the correct diameter in the beginning of the hole but after you get past the balls there is a ring there that is smaller than the post diameter. At first I thought it was an o'ring in the QD but now I'm pretty sure it is just molded plastic.
What the hell??? Are there different models of ball lock QD's and if so, how do I know which ones to get?