I always use some teflon tape on my AB/compressor/hose fittings too, cheap, easy to find, great aid.
Some adaptors I have ordered worked terribly, in some cases the thread pitch was way off, others worked perfectly. Buyer beware.
The threads are tiny, not robust at all, so I tighten minimally just until snug, relying instead on the teflon tape to provide additional seal efficiency.
Patrick