Personally, I think the 510 cartos sucked (air) too! I'll try (yet another mod) cutting one of the caps with a V... WHO WANTS TO BE A MILLIONAIRE??? Invent something decent to hold juice on a 510, that's all it will take!
Yes, I tried it on 3.7 and 5 volts. Yes, I tried turning the screw. (I killed one). I tried the condom method (filling the atomizer end and filling the threaded end).
The best I can find thus far is a regular cartridge with the plug method (cutting cart filler to about 3/8") in an atomizer with the threads removed from the atomizer. Still need to fill frequently! Somewhat, not as bad, inconsistency.
Cartomizers suck air and produced little vapor, th and flavor, as far as I'm concerned...
So, I'm going to go out on a limb...
Have you ever noticed that those who LOVE cartomizers are usually women, or people who where light smokers before vaping???