My pucks that I ran through the dehydrator and have sat for a week or so I measured and weight today to get a density. I measured a couple of pucks. It's hard to get a precise thickness because they tend to curl slightly during drying and also during pressing a thin rim extrudes between the piston and cylinder wall, which masks the true thickness of the puck. I try to let the caliper blades bite through this thin crispy rim to bottom out on the actual puck surface. The two pucks gave me a calculated density of 1.8 and 1.6 g/cm^3. So, I'm right at the 1.7 value I was my first batch. The first time, I let the puck sit under pressure for 5 minutes before releasing the pressure. This time I did not deliberately allow any dwell time, though sometimes I was busy for an extra minute mixing meal or whatever before I released the pressure. My press is the 12-ton Harbor Freight model.
My takeaway from this is that it is not necessary to let the pucks dwell under pressure.
I also broke my heart and ordered the $100 grain mill today. Busting pucks is such a chore and I hope this device makes it easier. I'm all about 2 seconds per puck like someone above said. I'm a little leery of the stainless steel rollers but since they don't touch hopefully it will be OK. I will make a point to do 1 puck at a time and remove the previous puck's remains from the area prior to grinding the next puck. Would be nice to take the rollers to a machine shop and have brass replacements made but I'm sure that would be at least another hundred bucks.
I've also run out of Potassium Nitrate so I ordered some more from Duda Energy and it has arrived. Now I have to grind it up as it is currently in prills.