update 10.4 changed the Heavy Caliber mod from increasing recoil, to decreasing accuracy, to "counter" recoiless weapons being able to use this mod without any negative effects. This however has an even greater negative effect on regular rifles, making rifles like the Latron for example, a rifle which needs it's high accuracy due to low damage, >40% less accurate. This has a lower impact on the Flux Rifle, which does wobble, but not very much, and automatic rifles, which do get less accurate but not enough to make them unusable.
however, shown below is what a rank 7 heavy caliber mod will look like (-40% accuracy) on [in order of appearence]:
Flux Rifle, Dera, Ignis, Ogris, Braton, and Soma.
hit hardest is the Ogris, making rockets fly dangerously far from the reticule. this may be good for some instances, such as spreading damage over crowds more effectivly. however, this also means that (1) your rockets can fly toward the ground, and kill you more easily (2) multishot rockets to not go at the same path as the regular rockets, meaning 1/2 the damage to targets.
Next hardest hit is the Dera. With already having annoying travel time, the added spread makes it a very poor choice for long range combat and suffers even up close.
it has little effect on the flux rifle, simply making it spread out in a round cone that is still about the size of an enemies head at it's max distance (at rank 7), and pretty much no effect on the Ignis, simply making the flame wobble around, much like the flux rifle, but due to it's cone-damage nature, this is not a problem.
on the braton and soma, accuracy is visably lowered, but overall not too much of a problem. think twice about using them with your Latron, Snipetron vandel, bow weapons, or Lanka though, as your first shot will not hit dead center and instead veer off to the side.