Ok first thing to do is head on over to Shiningbeam.com and pick up a Romisen forward clicky [ I got the 5 pack = Figured it might come in handy ]
Romisen RC-G2 forward clicky [ the one I got ]
Ok the first thing you need to mod is the AAA carier , it now needs to fit inside the tailcap ..
I used a file just to trim the Diameter just enough so the carier would fit inside the tailcap , its a tight fit .
Just deep enough to contact the neg spring on the clicky , and reach the + spring on the pill ..
Now to mod the tailcap for some more internal space so you can run a 18650 and have no issues .
Take out the guts , you do have needle nose pliers ground so that you can remove the retaining ring ? [ If not , buy some cheap needle nose pliers , and grind the tips to fit ]
Here are the parts you need , Rubber tailcap-boot , Romisen forward clicky , and the retaining ring .
Now you do need to remove the niple from inside the rubber tailcap-boot
Here is my boot turned inside out , nice and neat niple removal .
Make sure the boot fits [ if your using the original disregard ]
Next fit the boot to the Romisen switch and put it in the tailcap
Put in the retaining ring , and tighten
And there you go , Now you can run 18650's and not have a care in the world ..
Ok , it is a forward clicky now !!
So to change modes press but dont click for momentary on , to change modes , simply turn the light of and back on again [ momentary ] and you should be in the next mode , If you like the mode click on . Now you can no longer change modes without turning the light of , and doing the momentary on thing , enjoy !
Now I was able to use a Xtar 18700 with no problems , so hopefully this mod will work as well for you .