The force needed to pluck double bass properly is a lot greater than for bass guitar, and the technique is different.
^^this^^
And, it's not just force, it's also how your finger pulls the string. Especially with Dirty Guts, for pizz you're going to want to catch the string with the long side of the fingers (index and 2nd fingers or whatever preferred combination), not just the fingertips, with the fingers pointing mostly downward, parallel to the strings. You may also want to anchor your thumb on the edge of the fingerboard. I also found my Dirty Guts to be extremely quiet until I picked up this technique.
For me, the pizz stroke while slapping does use the fingertips. But it is a strong pull -- for me, i use Index, 2nd and middle fingers for that slap-pizz stroke.
And to be clear, while Dirty Guts in the production process start with wacker material (Kevlar core Gator line), their spiral cut sets them a large distance apart from plain wackers. They move much more air than plain wackers, and the texture from the spiral cut gives them a real affinity to both finger and bow, plus it keeps them from getting sticky in humid weather. Plus, for those who care, their touch and appearance is extremely gut-like.
Personally, I go back and forth about whether I want to go to real guts. If I ever do, I'll probably only go gut D and G, keeping my SilverSlaps E and A, but honestly it's a hard sell since my Dirty Guts D and G are really so good.
I'll 2nd (or 3rd) the lesson suggestion, btw. Some things you may be able to learn on your own and by reading about them, but having a teacher or a mentor to watch and learn from can make a big difference.