'Hulless oats' or streaker-type (nude) do have a loose 'hull', just to make the naming convention confusing. However, they are so much easier to thresh free than regular oats, so I understand the history of the name "hulless".
This is a Model No 99 from Grainmaker of Montana. For grain grinding, it comes with a pair of steel milling plates. Some of our experiments are being doing with the dehulling kit which are plates with a rubber layer that are used in place of the grinding plates. Sometimes I use one grinding and one rubber plate (just don't let them touch).
For small quantities, I thresh them free with a feed sack and rubber hose. However, I'm looking for more efficient ways to perform this task in large enough quantities to feed a family. Here I'm loading some Vicar Hulless into the hopper of my grain mill.
They are a bit 'fluffy' so I used a wooden dowel to push them into feed auger. I have found my 'nut' auger (top of the photo) to be more effective at pulling them into the mill than the (bottom) grain berry auger.
You can see the nut auger has the ability to grab the fluffy oats more easily.
Here is the gap between the metal flour plates I was using:
A video of the action:
They come out very 'dusty' and the hulls are quite pulverized. I started out with the metal/metal plates a little close, which might have caused a few extra broken groats. I took the output material to the barn and winnowed it to clean it up using my box window fan. There were just enough unhulled kernals that I decided to run it through the mill one last time with it set up as rubber/rubber for the dehulling plates. This was to give them as gentle as possible extra 'rub'. Sure, for this quantity I could have just picked thru and done it by hand, however, I want to have a well tested plan for dealing with a batch size of 5 pounds or so.
Here are the resulting oat groats:
In 1 1/3 cups of oat groats, I found 6 hulled grains... more than good enough for my purposes!