Actually they are a better design than that. The wire from the bottom end of the battery is soldered to the slug that presses against the 510. No funky spring current thing.I'll have to take a look
I was thinking too about what you said the other day about putting a mosfet in them. I had a pair of Megs coils on my green one for a few months that came in at like .11 or .12. 20S all the way. Not even a slightly warm button.
Of course we can't see inside, but you can tell that what we have here is that heavy slug of a contact and what is obviously a pretty heavy spring carrying the current. Seems to me (whatever that's worth) that unless somebody was going sooper low, like below .1, there shouldn't be an issue with this button as is. Just thinkin out loud.
I will likely remove and modify the switch and affix a mosfet and tactile switch and remove the slug so the switch operates the tactile switch. And solder a lead to the 510 from the MOSFET assembly.
As they are though I think they hit a bit harder than a Pico Squeeze. Slight drop theur a MOSFET. But no issues with contacts needing cleaning.