I've been using one of the Chicom air compressors from AGS (also available from Amazon) and it has no issues filling my 580cc/300BAR bottles on my two FX rifles. It does take it's time to fill, but it's always worked so long as you can plug it in somewhere or connect to 12v as it is powered by both. I usually keep a scuba tank with me as a backup in case I need to top up without having access to power. I have a buddy who dives and has his own high pressure comp so when I need to fill the cube tank, it usually cost me a coffee for the fill.