I'm an SLP and a person who stutters. Those are all "bilabial" sounds, which means you put your lips together to produce them. I have issues with /k/ and /g/...also produced in the same spot but one uses vocal chords and the other does not. It helps me to know where the trouble areas are so I can consciously make sure I can do things like lightly touch the roof of my mouth with my tongue when making a "k" sound instead of pushing it up there, which increases tension and makes me more likely to block.