There was one point in the 80's movie that showed a gun being used. Fired some sort of bullet or missile that went through the shield slow. Never saw it used again in the movie. You would think there would be clouds of those on the battlefield if they were useful.
Yeah, the book makes mention of "Slow pellet stunners" that could go through a shield, however it's not clear how a pellet or dart moving slow enough to penetrate a shield wouldn't have excessive drop or be nearly useless as a "gun". And that limitation aside, the dart or pellet would have to be very heavy to make up for it's low velocity.
And considering a shield would fend off even a knife blow at fast human speed, that's really slow, like slower than throwing speed. Considering it's possible to see and dodge Airsoft BB's and paintballs in flight at round 290-300fps without Dune super-skill, it just doesn't seem like a really feasible thing.
Although in the Lynch film, I kind of pictured the projectile that killed Duncan Idaho as some kind of hunter seeker. (more handavium give or take on how suspensors interact with shields) Where the dart was very heavy, and the suspensors kept it flying level, at a velocity that could penetrate the shield and keep on pushing slowly.
If I were to armor up troops for the Dune universe, I'd fit the guns with bullets that were small disposable laser pointers. Since a laser touching a shield causes them both to explode. Just have the laser bullet distance armed and boom. Although the lasgun/shield explosion handwavium isn't clear if it's the power supply or just the act of being touched with the laser that explodes.
