The Nanjg driver is rated from 2.8-6.0 volts so it won't work with an AA battery. I don't know of as any drivers that will push an XML hard enough with an AA battery perhaps you should consider switching to a 14500 IMR battery.
The pill is very light weight the walls are thin it's the only way you could make it to allow a 16mm star and 17mm driver to fit, but the threads are really nice.The pill gives great heat transfer because of the nice threads. Here some more pictures.
I just repaired an AKOray that I bought from DX months ago, the driver died when I tried a 14500 battery. I used a DX #25505 16.7mm driver that I sanded down to fit.
I see from the picture your pill doesn't have the included brass ring installed. How did you wire the negative pole?
That would have saved me some time, but more importantly I could have used a full sized driver, like maybe one of yours 8-)
But that host isn't that well made. I've had problems with the switch and the threads aren't that great. My review:
I wound up using the light as a host for a neutral XP-G. It works, but the switch is annoying. And the XR-E reflector isn't great for the XP-G.
I ordered this AA/14500 kit and may put a Nichia 219 LED in it (also have a Ultrafire C3 stainless on the way; honestly I'd rather put the Nichia in my Sunwayman V10).