Apparently the GPin that is included with the GP Paps v4 comes with different sized pins than included with previous versions. The new “long” pin is the size of the previous “short” pin and the new “short” pin is about the length of the pin that is used to make contact with the atomizer. I’m basing this on an email conversation with Vapourart Support.
Similar to cliffy, I am unable to use the new Paps v4 switch, a GP Paps v3 18500 tube, an 18490 battery, and a Heron direct connection because of battery rattle. Additionally, I am only able to use the new Paps v4 switch and top cap, a GP Paps v3 18500 tube, an 18490 battery, and a KFL without experiencing battery rattle unless I use the older “long” pin and unscrew the GPin from the Delrin insulator a bit.
I understand that changes must come with innovation and that Vapourart tries to offer backwards compatibility as much as it can. I’m content that my primary use case of using an older 18350 tube with the new “long” pin works fine, but I can envision a new GPin kit being offered that includes a variety of different sized pins like the new “short” and “long” pins, the old “long” pin, and a newer “longest” pin that can be used to support the two scenarios that I describe above. Perhaps these pins could be sold separately so pre-Paps v4 and Heron owners could buy just the old "long" pin and/or a new "longest" pin. I imagine that options like this would be attractive to people like me with legacy GP Series products that want to be able to maintain compatibility.
We can create a longer pin just for the direct connection of Heron+18500 tube v2.5 or v3+AW 18490 battery+switch v4. In all other cases there is nothing else needed.