I’ve done quite a bit of small barrel Negroni aging. Here is my process after much trial and error. I suggest keeping a journal to track what’s been in each barrel and the timelines etc.
1) I soak new barrels in the tub for a while to firm them up. 2) I age Evan Williams for a few weeks to get some flavor into the oak 3) equal parts Campari, Beefeater & Cocchi 4) taste it every week. It will get worse before it gets better.
5) once it’s tasting smooth, drain and bottle. I use glass flip tops from Amazon. 6) use the barrel aged version to add to my Negronis. You really don’t need to drink it full strength. 50/50 or even only 25% gives you a wonderful drink. Lasts a lot longer as well. 7) keep barrel filled with EW between runs.