@Katya, it seems that a lit of mods released recently have had issues with the 510 connector. The only explanation that I can think of is that they must be employing designers, when they should have employed engineers.
And it would be nice to see more mods with a reimagined and reengineered fire bar solution, as it could be better done and is easier to use for some as @amoret has pointed out.
I agree. Just googled it. There are some mods with side fire bars out there, like vaporesso Armour Pro and VaporFi V-Grip 75W, but I don't know much about them.