Honestly i don't fully understand what you are tying to achieve. You want those valleys to be smooth? Or to be crips but front be smooth? In my opinion you are using to low geometry for that kind of shape.
Step 29, as it left a hard edge after the weld. I used paint deformation and smoothed out the verts with the relax button pressed. Just paint the area that looks hard edged to smooth it out.
Gorgeous. The neck roll is a good idea, maybe with a neat button-on setup or something to break the shapes up between the smooth metal and [presumably] smooth cushion. This is looking amazing already. Excited to see more!
You have some really great smooth shapes going on there, except for the hair. I would add some more density to the hair and smooth it out a bit so it looks consistant with the rest of the model.
Yep, smoothing groups aren't a thing in zBrush (or most applications really). You could use auto crease and subd that way, or sub-d a bunch in max using smoothing groups, and import that (heavier) file into zbrush.
Most of the time I start with a smoothed object and then lightly chip away at the corners with the trimDynamic brush. This gives me a balance between a smooth shape, and defined planes which I feel helps sell the definition of the shape.
Double check your smoothing groups on both ends, it seems as if they have the same smoothing as the barrel and the stock without actually sharing uv island. Probably just a textool error that can be easily fixed it would seem ?
The pink lines are the hold loops and the green the general topology. If this what you're looking for? You can also trying using (In Max) TurboSmooth with "by Smoothing Group" on if you assign different smoothing groups for each 'flow' of the mesh.
Try Normals>Conform as a quickie, but your geometry could be messy, and/or could have polygons facing the wrong direction. Go into smooth mesh preview; anything that doesn't smooth properly is something you'll need to look into fixing.
Just a quick'n dirty neutral expression test with the new topology in ZBrush. Gonna redo it though, because I need to keep the polygon flow smooth. Not that it's not looking smooth already, but that extra push to perfection helps. :D