Which bulb will handle 6+ volt for Twin Task

I have a Streamlight Twin Task 2L. I am using 2x rechargeable cr123 batteries. Each battery is rated at 3.0v I burn out my original Twin Task bulb due to stupid charger overcharging battery each time. Question is, is there any bulb out there I can buy that will fit the Twin Task's Bi-pin base? I don't mind if I have to drill out the reflector to make it bigger, I just need it to fit the base. I need a bulb that can handle at least 6 or more voltage. I'm not an expert when it comes to electricity but I am guessing if I have 2x rcr123 at 3.0v each, when fully charge, it's discharging about 6-7 voltage; maybe more. Correct me if I'm wrong. Thank you for any reply.