Surefire Lego question

After reading through seemingly countless posts regarding the cross-compatibility of surefire parts between model ranges I still can't find a definitive answer to help me with a query. I have a bored for 18mm cells Surefire 6P that I use a A19 extender with to enable me to run two 18500 cells. Can I add another A19 extender to screw into the back of my existing A19 to enable me to run 2 18650 cells? If they do not mate I would have to use a 9P with my A19 extender to run 2 18650?

If anyone can answer this question it would be very appreciated!

P.s. All the parts above would naturally be bored to suit 18mm cells.

Phil40000 said:

I have a bored for 18mm cells Surefire 6P that I use a A19 extender with to enable me to run two 18500 cells. Can I add another A19 extender to screw into the back of my existing A19 to enable me to run 2 18650 cells?

Click to expand...

Yes. Extra joints reduce overall strength, but the geometry works.

Phil40000 said:

After reading through seemingly countless posts regarding the cross-compatibility of surefire parts between model ranges I still can't find a definitive answer to help me with a query. I have a bored for 18mm cells Surefire 6P that I use a A19 extender with to enable me to run two 18500 cells. Can I add another A19 extender to screw into the back of my existing A19 to enable me to run 2 18650 cells? If they do not mate I would have to use a 9P with my A19 extender to run 2 18650?

If anyone can answer this question it would be very appreciated!

P.s. All the parts above would naturally be bored to suit 18mm cells.

Click to expand...

If your question is whether A19's will "stack", the answer is yes. A "6P+A19+A19" will be approximately the same length as a "9P+A19", and roughly the length of 4x CR123A cells (approximately 138mm). Note that 2x 18650 cells will be (theoretically) about 130mm, though protected cells are usually 19670 (slightly larger, due to the protection circuit and wrapping), so 2x (protected) "18650" may be about 134mm, and perhaps still a bit short without a spacer. There may be even more variation in length, depending on if the poles are flat-tops or not.

Note that I haven't tried this combination personally, so these are guesstimates. Of course, you also have to be aware of voltage issues with these "lego" setups, as well (though 2x 18650 will be the same voltage as 2x 18500).