Headspace in Barrel

[MysticX]

I recently picked up a 15 gallon whiskey barrel and filled it with what I thought was enough 9.5% stout, but came a bit short of fully filling it.

Should I just put in some fresh wort (and separately ferment out some more beer to use to top off later) and would that still ferment? Should I instead separately ferment out some more stout and then add that back in after a week or two? Unfortunately, the only other beer I have sitting around is a mild, and that perhaps would not meld well with the stout. Thanks!

 

[MysticX]

Or I guess another option, just buy some stout and pour it in?

 

[1977Brewer]

You're fine with the headspace. It will make beer.

 

[ArcLight]

You're fine with the headspace. It will make beer.

You most certainly are NOT fine with the headspace if you plan on aging it, unless you want Oxidized beer.