When I started to look at voltage drop on my Grands I found that my voltage was dropping about .9 volts with a fully charged battery on a .65 ohm coil.
Soon after I employed Pdib's brass shim, and my voltage drop decreased significantly. After brass shim it was about .35-.4 volts. I decided that wasn't good enough, and Rob answered my prayers by saying that he was coming up with a sub-ohm kit soon. I, being impatient, couldn't wait. Here is what I came up with
What you're looking at is my brass firing pin. I had a firing pin go bad (point flattened out from overuse, at least that's what I am going to call it), and I used that as my template. Bought some .007 thick brass shim stock, cut to size, drilled the hole, and in it went.
I was kind of scared to hit the button at first, but then I remembered buying at least 6 extra hot springs since my first Reo experience. With my tankometer on my baby I hit the button
3.93 volts, and no melting spring (also no Noalox on firing pin). So far, so good. Screwed my RM 2.0 with a .65 ohm coil onto the tankometer, and VOILA!
3.74 volts! That is a voltage drop of .19 volts.
It worked so well that I made a second one for my other Grand, and that had a voltage drop of .2 volts. Also, the picture in this post were from about 24 hours ago, I just changed the battery, tested again, and the voltage drop was .22 on the black Grand. Consistent enough results for me to call this a success. Now I need to make one for my Mini 2.1.