I went with double braids on mine… Just sent it out this morning… Goodbye sweet light. I tried DBC method and I couldn’t get the spring to compress enough. I have to try that copper button top OL.
If you have a good electrical path and good copper heat path to the pill, you can go dd without noticeable sag. 
Agree with OL- unless you don’t plan to braid. Intl has the best but like 3 bucks a spring 
Better come with some boobs
Djozz,
You are hard worker and you are 100% into your hobby...
Glad that you tested that Phosphor broze springs because I new that they are better than original steel springs only by my luxmeter, always 10-15% more brightness when I swap steel with this phosphor bronze guys (they look like a copper to me).
Your custom spring looks excellent. Need that kind of spring with ∅ 10mm bottom base and 11-12mm height. This springs are much more flexible than steel ones and they are battery friendly not pressing pcb so hard as steel. Excellent for single cell 18650 lights up to 3A.They also accepts solder paste better so they can be braided or wire bypassed to if needed.
I tried braiding steel springs with braid and wires(contact and switch) but lux results were same as stock until I tried copper bronze ones. I really don't know what happened but lux number instantly jumps.
I only wish to try beryllium copper springs but no one has this puppies(at least at China stores).
I found some interesting suppliers for copper like springs here: http://www.aliexpress.com/item/Free-shipping-Phosphor-Bronze-spring-for-flashlight-DIY-100-pack/1062864560.html and here: http://www.aliexpress.com/item/10X8mm-Solid-Copper-Spring-For-High-Output-LED-Flashlight-Driver-Circuit-Board/2054366124.html
The phosfor bronze springs that you link and the Fasttech one are all about the same size, perhaps they all sell the same bit smallish spring?
Nice springs and nice work! There is nothing wrong with them and given the "actual size" (diameter and length of "wire") you are almost neck and neck with CB springs. If you are willing to dispose of some at the cost you mentioned you may get rid of the majority. I would definitely take a few to a dozen ;)
Yes it seems all selling same stuff. There is only difference in their description (copper, carobronze, phosphor bronze).
They should get more sizes for them, and more thickness options although you can rework them with some conical tool (strecth here and stretch there) To bad beryllium springs for flashlight are not broad on the market...
Hank of intl-outdoor asked me about the precise height of the tested intl-outdoor spring. I understand he is concerned about tests of the springs that he sells. I post my answer to him here as well because I think that it is fair to tell any concerns about my limited tests.
Yes Hank from IO should not be to concerned about this issue this is small spring anyway and most of springs will compress a bit especially when they are tight fit with battery.
Springs with bottom base from 9-10mm and height 10-12mm thickness 1mm are most common bigger springs. Hank as your old buyer please get that famous Beryllium copper springs...
For bigger springs my vote goes to this dimension: ∅ 10mm bottom, height 11mm, 1mm(or bit larger) wire thickness which should fit to most tail switches.
or smaller one: ∅ 7mm bottom, height 10mm, thickness 0,8mm (that could replace nanjg spring also)
Thanks for the testing Djozz 
Thanks for the great testing. 
Did you see Simon / Shenzhen Convoy Electronics carries Phosphor Bronze springs? $2.75 for 10. High 10mm, bottom diameter 7mm, diameter 0.8mm.
Orange coppery color from the picture, for whatever that is worth.
They sure seem identical (size and color) to the FT ones: fasttech.com - springs djozz listed in the OP and tested, just over twice the price.
Thanks djozz for your effort writing, thinking, testing, photographing, editing, uploading, copy, paste 
Thank you any way
So what’s currently the best recommendation for springs, and for bypass wire — for ordinary lights, and for hotrods?
And does anyone make springs with bypass wire already connected (say with a spot-welder)? Because I find it hard to get bypass wire soldered to each end of a spring without overheating the whole spring.
Try to put a little dab of flux on the surfaces (the wire end & spring) you want to mate with solder, and you will find that you don’t have to heat them so much to get them nicely joined 
For all lights that have to perform a little bit I would do a spring bypass, except if the light has to be particularly good-looking, i.e. if they are meant as a present, then I'd go for a copper-alloy spring without bypass, looks way better! (I have a djozz-spring without bypass in the tail of my BLF-X6, with a LD1 driver and a 80CRI 3500K XM-L2, now that is a chique light! ) But a serious single-li-ion hotrod needs a complete spring bypass, a copper spring is not good enough.
BTW, I could ask the manufacturer of the 'djozz-spring' to make another batch if there's interest enough, I still have some and really like them for the bigger lights. In case of another batch of 200 pieces they would be a dollar/spring again (plus some shipping, see my old spring-sales-thread). what I would do different is that I would have them made with 9mm base instead of 10. Probably the height would then be a mm less too.
Thanks for the great testing.
It looks indeed to be the best of both worlds. (almost) the strenght of steel, combined with (almost) the conductivity of copper.
Having said this, I’ll hop over to your spring sales thread to order some.
If you had another run done, I’d definitely be in for some. Maybe 25-50? Timing dependent, 100?
(it was a real bummer when I used the last of my djozz springs)
Edit: And for what it’s worth, I like to clamp my curved jaw hemostats on the coil of the spring just below the end I’m soldering the wire to, then do the soldering with the solder wire directly applied to the spring/22Ga wire to get the most of the resin core inside. The stats absorb heat to keep the entire spring from overheating.
Flip it and do the other end, then you already have solder on the spring when you solder it to the switch/driver pad, which makes that go much easier as well.
The exception is when bypassing the pcb the switch is on, in which case I like to remove the switch, mount the spring, solder the wire to the top of the spring once passed through the board, then replace the switch and make the wire to switch connection simultaneously while attaching that side of the switch to the board. Again, clamping the stats to the part of the switch lead that comes out of the plastic housing keeps that connection from melting the plastic. This process keeps the switch pristine, so it’s not overheated internally and works smoothly.
Gosh, takes much more to say it than it does to simply do it.
good thread.. came accross this post from below thread
in a similar power bank the voltage drop at .5A was 110mV from one end of the sprint to the other end on the pcb.
Sorry for bringing a shovel to a flashlight forum, but I had to dig this thread up.
Never seen this test before so it’s really interesting to read all this information.
So in short. If you can, bypass the spring. It can only do good.
Really have to try that to some of my lights. luckily the (only real) hotrod with the fet driver I have has already both springs pypassed.
Yes, an interesting test indeed!
I did my first bypass a couple of day’s ago, the smallest one shown in this test - 5mm tall spring from a Qlite/ Nanjg driver. So frustrating trying to keep it in place whilst soldering.
The spring is so small it needs to be stiff to avoid being compressed too much, if you drop the torch vertically on it’s head it does very little to absorb the energy of the heavy cell’s, I dropped mine the other day and the button on top of the Panasonic cell just collapsed, the driver was fortunately still intact.
I’m going to see if I can find a taller softer spring which I can then braid.
I know #8 wasnt the top performer, but ive been looking for a source for that spring. i had two of them. I believe they were added to a driver order from mtn. The reason im looking is that they fit perfectly over the top of the nanjg spring to give a little compression before the battery presses on the stiffer nanjg spring. anyway, if anyone knows where to get them, please let me know.