Yes, plug 'em in all the way BUT, what I do on a lot of them is squish the bullets a little bit together with a small pair of needle nose. If you get them too loose, just stick something in there to spread them back out again. They vary quite a bit from connector to connector how tight they are. I've probably had to squish about half of mine together to make them easy enough to pull apart. You can kind of "tune" how tight they are using this method. You don't want them to loose, you want to keep a reliable connection not to mention you wouldn't want it to come apart in flight.
Thanks, that helped a little. I think it's because the original XT-60's are such a perfect fit that they create a suction cup like effect...
But my connector won't open in flight.