"pulling only 190 milliamps out of 4.3 volts"
The reason is too control the heat, not much of a heatsink in a PR base.
I've made a home made one (see thread) and it draws 400ma with freah batteries. After a couple minutes it gets real hot. I've not done any 'burn in' test, but have used it for 5 or 6 min periods without any problems.
I modified another 3D mag to install a round heatsink into the tube, and mounted the Luxeon on a short stud (to get focus). It draws about 500-550ma, and seems to not get near as hot. It's real bright.