Early Surefire 6P Dropin Compatibility Question - HELP

I hope I've posted this thread in the right section.

I have a very early Surefire (Laser Products) Round Body 6P flashlight. I was wondering if the new custom P60 type dropins will fit in this light. It doesn't have the removable bezel ring. The bulb assembly drops in from the rear once you remove the head. I was planning on retaining the push for "momentary activation" / twist to activate "constant on" tailcap too. Would also love to hear suggestions as to whether I should limit how far I go with my dropin choice. Any help would be greatly appreciated. Thanks.

This is the dropin I had in mind: EDCPlus X60L 1-mode Warm White T4 Cree XM-L Drop-in For SureFire

Specs: • Powered by Cree XM-L T4 Warm White 80 CRI • Modes: 1 Mode (High) • Current: 1.5A +/- 100mA • Input Voltage: 3-6v • Supported...

Do you have a micrometer. IIRC, it should fit.

awenta said:

Do you have a micrometer. IIRC, it should fit.

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Thanks for responding. I do have a cheap mic., what am I measuring?

jkid1911 said:

I have a very early Surefire (Laser Products) Round Body 6P flashlight. I was wondering if the new custom P60 type dropins will fit in this light. It doesn't have the removable bezel ring. The bulb assembly drops in from the rear once you remove the head. [...]

Click to expand...

I have a number of early SF's that utilize the older head assembly as you describe - although they are slightly shorter as measured from outside dimensions, internally they seem to be exactly the same length (and ID as well I would guess), with regards to the dropin fitment surfaces. I have used various high-performance LED dropins in them and have never discerned any fitment difference at all.

If you really wanted to do some checking, here are two dimensioned drawings I have done on SF's of relatively modern production. I have verified the P60 receptacle dimensions of the older light bodies and they are correct to a few thousandths. I have not measured the internals of the pre-Z44 assembly; if you do please let me know as I would be curious as to whether the internal dimensions have been held constant over the years. My guess is, probably.





Hope this helps,

jkid1911 said:

I have a very early Surefire (Laser Products) Round Body 6P flashlight. I was wondering if the new custom P60 type dropins will fit in this light.

Click to expand...

I haven't tried any fully potted drop-ins, but I've always been able to interchange other drop-ins between my round-head and hex-head 6Ps without any issues.

Wow, you folks are AWESOME...!! Hey Kestrel, thanks for such and informative post. I'm going to need a better mic than I have to get some ID measurements, but for now it would seem that there is no issue using the same dropins in my round head 6P as my z44 ones. Thanks.

The various P60 drop-ins should all work in the old round body 6P, whether you use the stock round bezel or the current version bezel with the hex flats. I've tried various DX and KD Chinese drop-ins, OpticsHQ drop-in, and Malkoff M30 drop-ins. All function fine.

However, a perfect fit is probably the challenge. Quite often, you get a small gap (~1mm) between the bezel and the body, i.e., the head doesn't quite screw down completely. This doesn't compromise function since the o-ring seal is fully engaged, but it looks bad cosmetically.

In the old days, folks experimented with removing the outer spring from the P60 drop-in and that sometimes helped reduce the gap. In my limited observations, the hex flat head also helps to reduce the size of any gap.

Rarely, you get a drop-in that doesn't seem to make a reliable ground connection to the 6P's "neck". Typically, a little reshaping of the bottom edge of the pill provides for better conformality with the interior profile of the 6P neck and improved electrical continuity.

+

Later 6Ps have a fully silver P60 socket. Early 6 and 9 Ps have an anodized (insulated) socket, with an edge at the bottom of cut metal. In practice, this works like the top of the metal sleeve in a G2,

Example of unanodized vs. anodized SureFire 6P/6Z necks. Note the bare (unanodized) rim, which is where the outer spring or brass pill of a P60 drop-in makes its ground connection. As EG states, that contact is analogous to the metal sleeve in a G2.

But even in such a case it is not difficult to remove the inside ano.....
The process is documented here and it is not that hard

Yes, one can remove the Type II anodizing using the same approach as with deanodizing the inside of a Maglite tailcap. Pour in some drain cleaner, wait some amount of time depending on the concentration of the lye in the drain cleaner, and wipe/rinse off the dissolved anodizing. However, this is CPF and abusing an early gen SF 6P like that ought to be grounds for banishment from the fraternity of flashaholics!

Interesting.
My round head 6P (not sure how early - S/N A027820; tailcap says surefire; P60 incan module said Laser Products) is NOT anodized in the neck (or body, either) of the tube. It does not look like it was stripped. Very similar to the one on the left in justin's photo, except a cleaner transition where the ano ends.
Regardless, I have used it successfully with 2 Malkoff M61's, a NB P60, an EDC+ P60, and Mac's triple P60.

It's hard to say how much gap there may be internally, but all feel solid with no rattle. I don't leave them on "Hi" long enough to adequately test heat transfer, except one time I forgot to lock out the tailcap and my M61W was on overnight in my jacket pocket. In the morning, the light was quite warm but not too hot to hold. Output was dim. Replaced batteries and suffered no ill effects.

I doubt you'll have any problem.

The lights shown above in post #9 are at least 15 yrs old. The tube on the left in #9 also looks like it has no ChemKote.

If your 6P has a serial number on it, it isn't old. The 6Ps I've seen from around the late 1980s through at least the mid 1990s had no markings on them except at the tailcap. I have one newer 6P that I believe I bought around 2000 that has an oval flat on the body and a big SureFire logo. I can't recall seeing a serial number though and the light is currently not accessible.



If the tailcap doesn't say Laser Products on it, it probably isn't very old either.