The detents and loader determine if its going to double feed. Mostly its the detents, because even weak detents will generally hold back paint enough to stop a strong loader. The caveat to that is paint that is really small. If you have a larger breach, which is most paintball guns, then small paint can go around the end of the detent. When that happens, you can't stop it, even with stiffer detents. The only way to stop this, is to install a second detent on the opposite side of the breach from the original detent. A second detent reduces the width of the breach by the length of the new detent.
Except for the Automag in front, its usually the man behind the equipment that counts.