6 watt laser build, host tail cap can't handle the current

So I recently built the strongest laser I have ever made, and have ran into a problem.

Everything went together fine, and after a 5 second "on" to test, I took out the batteries to test current draw to gauge the life time of one charge.

Right when I took off the tail cap I smelled the all to familiar burning electronic smell. I tested the driver and LD through the meter and it lased just fine, drawing 3 amps. The laser itself wasn't starting to fry so that's good. Then I smelled the tail cap because it felt a tad warm. Sure enough, that was where the smell came from. I put the cap back on and kept the laser on for about 10 seconds, turned it off and brought the top part of my lip near the spring. I could feel the heat coming off of the spring, and it actually oxidized a little turning slightly black.

So I guess the tail cap isn't rated for 3 amps, but I think it's more the spring being how thin it is. :(

I did some searching and couldn't find any high rated tail caps. And even if I did they would most likely not thread correctly.

The host is survival lasers s4 host and the diode is DTRs NUBM44-81 6 watt with driver. Now, I was going to put it in the s4x host for the extra heat sinking but they didn't have an adapter yet for the 20mm modules. Both my 1 watt green, and my 3 watt 445nm are in those host and I can run them almost forever.

If anyone has an idea as to where I can get a higher rated cap that fits the s4 host or maybe how to mod the spring, please let me know.

Thanks!