JNdeer is spot on. Kifaru lite frame doesnt slip on me, likely due to lumbar pad surface material. However k4 overall is more comfortable, but it has taken many adjustments so far to get it that way. Exo mentioned shoulder straps/torso adjustments were finicky with k4 and I agree.
For me, I...
Theres a variety of brushes on Amazon, some of the smaller ones for a water bladder will work. Or baby bottle brushes sometimes will have a smaller brush in the handle.
I learned how to properly shoot the releases I have. Spent a lot of time back and forth adjusting an index release In length. Also having a mental shot process in place.