Hello everyone!
I just finished my comparison video of two Convoy flashlights (sorry, M3 uses 26650 battery but as it is one video, I decided to post here) with Cree XHP 70.2 emitters.
Hope you will enjoy watching. As always suggestions and questions are welcome 
Convoy M3 XHP70.2 5000K:
Also turbo M3 vs M21C-U
Pretty similar performance. I think the M3-C has an “updated” driver, so would expect some changes to performance to the M3?
M3-C has lroblem with contact at head. Tailcap spring is too soft for 26650 battery and when you shake flashlight, it blinks (loosing contact). But I would guess UI is updated. As I said in review, I do not understand why they put those cilinder contacts in head… at least it would be like spring moving(have it in cheap hardware store flashlight).
Performance is good, I would even lower the output like it is in M21C-U for longer access to turbo. Now 3.7V is minimum for M3 with xhp70.2
Extra pressure is needed so. My solution with the P60 outer dropin spring. There is enough tension that the spring stays in place when the tail cap is removed. 
The brass post contacts do serve a purpose but yes, spring on the M3C is inadequate for heavy cells. I don’t know if Simon is actually going to address this light but it looks like maybe not. In the L8 he did use a very beefy spring of the same design but he was indicating in the main Convoy thread that maybe it wasn’t suitable for the M3C…I may go ahead and take him up on the offer to get a couple of those spare beefy springs and see what happens. I did the P60 spring like texas shooter and it mostly works. Can still cause the light to turn off in lowest modes with a good bump, but the additional spring pressure does help a lot.
Texas…did you remove the retaining ring entirely? Hard to tell from your pic. I just sat mine on top and have to carefully assemble the light to keep the spring in place. I tried bending a short 90° nipple so that it would rest in the retaining ring hole but neither that nor widening the wire curve would hold it securely on/at the retaining ring. Kind of an irritating problem and I wish Simon took it more seriously because it seems like an easy fix even if he wishes to keep the overall single-spring design. It’s a great light really, quickly became a favorite and a standout in my collection for its sustained output if nothing else.
Simon sent me a heavier spring for my M3-C. Works better.
The M3-C I received the tail spring was held in by the triangular tail spring base only, no retaining ring. The P60 spring is slightly larger than the spring pit. Only slight pressing or twisting is needed to seat it on top of the base spring. Bounce is gone with both the 26650 and the 26800 with extension ring. If your spring is being stubborn then just tuck the very end under the triangle primary spring base. Let the first hold down the extra.
Thanks for the info. I have a M3-C on order, so will try this if I experience the bumping issue.
Interesting. Mine, which I ordered directly from him just about a year ago, has the triangle spring tucked under a shelf in the bottom of the tailcap, and then a brass retaining ring threaded in on the top. I’ll poke around this weekend when I have time, see if removing the ring might give a better tension fit for the P60.
Pennzy, could you get a photo of the new spring he sent you? I hadn’t heard anything about a heavier spring except the new L8 superchunk spring….haven’t seen what any of the earlier M3C springs may have been like, though.
I’m pretty sure it was this one
Ok. That’s the one that came stock in my light, with the .9mm wire.
That’s what’s in mine.
Ok, so I removed the retaining ring and was able to poke the P60 spring down on top of the stock spring with an ok compression fit…easy to booger up the threads, though. That reduced the height of the P60 spring enough that I decided to stretch it out some and the end result is still a little blinking but it no longer cuts off from low mode with a bump. For grins I tried it again with some of his pcb board spacers, just one on the + end and no improvement. I think I’ll ask for one of the beefy L8 springs on my next order with him and see how that goes. If it’s too stiff then maybe Simon could be coaxed to source some springs with a middle-of-the-road 1.2mm wire as a better simple solution if reverting to a driver with a spring isn’t in the cards.