The V10R Ti has an O-ring groove that measures identical to the Surefire E-series. Since Ti is roughly 2X stronger than Al the light should work well when bored for 18mm cells. Think of an E1E or E1L on steroidsIs there enough meat in the body and extender to bore to 18mm (will allow the use of 18500 and 18350 if the body is long enough).
Price to bore the body for either 17mm or 18mm cells is $60. Boring the extender is $20.