Having come from a military family and background, it's particularly important to me to acknowledge that today is not just another 3-day weekend but is a day for remembering those who gave the ultimate sacrifice in service to our country both at home and abroad. Without such brave men and women answering the call across multiple generations, it would not be possible for us to enjoy the freedoms we do today. 
Today was a particularly productive day at the work bench...the weather topped 100 degrees outside so I had the perfect excuse for staying indoors. First order of business was to work on the Flak 38s, so I returned to Step 15. The kit supplied parts are highly detailed but the one area that styrene limitations really show is in the flash suppressors on the gun muzzles. While DML molds the openings hollow, the slots on the neck and the holes in the sides are only molded as slight depressions. So I turned to my trusty source, JB Models, for some turned aluminum and brass replacements. The aluminum barrels come with separate brass suppressors and the opening in the suppressors needed to be opened up slightly with a round needle file to fit the barrel neck but otherwise assembled without any problems with a little CA gel. JB Models produces don't come with any instructions, so you need to be ready to figure things out on your own. The small PE fret included the barrel release catch and this was added with a small amount of CA gel as well.
The styrene kit barrels were cut away from the receivers with sprue cutters and then the ends sanded down with 400/600 grit emory board to the right length. Using a sharpie, I blackened the ends (this allows for easy determination if the hole being drilled is centered or not) and then used a pin vise and drill bit to create the required holes to accept the mount pins on the end of the aluminum barrels. The barrels were then joined to the receivers using CA gel and the rest of the gun assembly completed with the addition of the top housing and locking bolts and 2.0cm magazines.
Step 17 deals with the turret and assembles it from the two shell halves plus the circular ring insert. I found it was much easier to install the ring insert first and then add the rear half after as it provided more surface area to glue and work with in terms of getting the rear and front halves to mate up correctly. I glued the base of the rear half first and let that set up, then worked one side at a time with liquid glue to insure a solid and square join on all sides. The front direct-fire flap was added (it's part D17, not B17 as called out in the instructions) along with the hinge parts, D19, which the instructions don't provide a parts number for and just show already installed. I opted for the closed position and installed the two PE retaining clasps using careful amounts of liquid glue to secure them in position.
Step 18 adds the turret interior details. I installed the two loaders' seats but only added the base parts for the ready ammo racks. The additional parts to complete the racks have the magazines molded together so for detail painting purposes those will get added later. The backs and bases of the racks had large shallow ejector marks that would be partially visible after assembly so a little bit of sanding work took care of them.
Step 19 wants you to add the Flakvierling directly to the turret, that will get done after painting so that was skipped for now. Step 20 directs you to add the PE supplied spent shell casing collection chute but you can do this at any time as the installation doesn't interfere with the fit of the Flakviering with the turret...I think DML left to this point as it was the most convenient spot for it and/or they forgot to mention it in the earlier Steps dealing with the Flakvierling. The PE part doesn't have traditional bend lines but instead has perforations which makes for a sharp bend on the first attempt but don't over-do it as bending it back will make it fragile and possibly damage/break it in the process.
Step 21 is the final step, it shows the install of the turret to the hull as well as the addition of the tracks and spare road wheels. The tracks will come later after painting as will the road wheels. The diagram shows the base of the turret ring, part D22, installed in place but doesn't call it out with a parts number so be sure to add that so that the turret will sit correctly. I did a quick test fit to make sure everything would play nice with each other and the fit is snug but perfect.
Aside from the MK tracks, major construction is at an end and will be moving into the painting stages as the next step.