I've been fermenting beers in 10 gallon cornie kegs for a while. So a few months ago I came up with the idea of fermenting apfelwein in a 5 gallon keg.
Poured almost all of the five gallons of juice into the cornie keg. Then Pitched the yeast and attached an airlock I had made to the gas in post of the keg.
Everything seemed to be going fine until the airlock began leaking out a small amount of juice. Turns out you should leave a bit of head space in the keg. Put the keg in a bucket and let it sit. Cider still tasted great.
Next time I only did about 4.5 gallons and everything worked out well. I haven't cut the dip tube down and it only pours yeasty for a pint or two. I use the same keg for fermenting and serving.
Anyone else done this?