A bit late on the draw on this ... and I don't have advice on the German 17cm Kanone, but I want also to provide some level of reply to this issue buried in the original post:
Schwerepunkt wrote:
I am getting some hexes and plan to use grass and other scenery. I have some 1/2 x 1/2 bases cut out of cardboard for my dismounted infantry. How does one put grass on those or do you just paint them green or brown?
Schwere:
Don't worry about newbie questions. We seem to have a pretty friendly forum here, and I don't recall anyone getting bitten yet.

We were all beginners at some point, and some of us (like me) were "beginners" for a looonnnnggg time (like a couple decades, maybe?).
Seriously, I have been collecting and gaming with Microarmor since the early 1970s. I didn't really belong to any sort of "gaming club" for most of that time, and so didn't have the benefit of others to show me the ropes. My own painting skills have improved by leaps and bounds since finding this forum and joining in the discussions.
So, to the point of your comments/questions ...
I have used several different approaches to basing my infantry, including cut cardboard. You will see several different approaches described in these discussions, and I strongly recommend the current tutorial that Ritter (our resident Ubermaster of Microarmor) is running.
But to this one point -- I rather recommend against cardboard for basing your figures.

There are some of my early war French, not posed for a photo but in a candid shot from an actual game. My French were done in the early 90s, and at that time I was using cut cardboard.
I observed three shortcomings from this as a basing material. First, and perhaps obvious from the photo, is that it is almost impossible to keep the edges from fraying. As they fray, the discolor to whatever is the natural color of the cardboard (probably off-white or light gray). This makes your stands "stand-out" as if outlined in off-white. Not visually attractive.
The second disadvantage is the extreme light-weight of the cardboard. Easy to carry perhaps, but the infantry will never be a big part of your army's weight anyways. The problem is if you get any wind on your game table. I play in my garage, and it is easy for a breeze to come in under the door, but with cardboard even a sneeze from one of the gamers can set a platoon off by a couple hundred meters (in game scale). Or a bump of the table will jitter them out of position. I like a little more weight, so they stay put.
The third disadvantage is somewhat related to your question about getting the "grass" onto the stands or just painting them. I paint my stands first, and then I put model railroad "flocking" on them. Usually I paint brown (or some dirt-like color), and add a green grass flock. I add some other items to the flock -- a little bit of model railroad shrubbery (crumbled foam) and maybe some larger grit sand (from my kids' old sandbox out back), just to provide a little variety. Others here are more elaborate with model railroad "static grass", and I will by trying that with my next set of figures.
But here is the issue: with cardboard, I can't provide any "texture" under the flocking. I like to build-up the tops of the stands to help blend in the bases that the infantry figures are molded on. In the past I've used a thick layer of white glue, or modelling clay, or grouting. More recently I have bought a tube of "textured paint" at a crafts store, which I think works very well. But in any of those cases cardboard bends much too easily, and so anything I apply on top of the stands (including occasionally the infantry figures) will either crack or fall off when the stand is torqued or bent in any way. And so while you can see in the picture that I have flocked the French infantry stands, you can also clearly see the bases of the infantry figures.

By way of comparison, the Italian infantry in this picture (from the same game) are mounted on pennies. Cheap and readily available, strong and with some weight to them. The bases of the infantry figures are effectively blended in to the texturing I have added to the tops of the pennies before flocking. The picture doesn't quite do justice to the edges of the pennies -- I chose to paint the stands "Sahara Sand" which is a beige tone with a bit of green ... maybe not the best choice in the end, but certainly not as white as it may appear in this picture, and not as visually unpleasant as the frayed whitish edges of the cardboard base of the French infantry stand in the background.
So I recommend against cardboard. I say find something more substantial.
Just my $0.02 worth (or maybe .01 worth given my prefered infantry bases).