Check your tube diameter. I have a craptastic ‘as seen on tv’ type zoomy light that has a 3xAAA cartridge. I’m glad I didn’t throw out the weird plastic tube that was in the box, as it lets an 18650 fit. As an added bonus, the 21700 from a C8F fits nicely too!

Yours may not be wide enough, or the extra length may be a problem, but if you can get access to a cell, it is worth checking out.