You must have a really top notch pressure cooker. When I cook pintos, for example, I soak them overnight or until they are all swollen and non-wrinkly, rinse well, and then bring to pressure (mine is not fancy, doesn’t have any gauges), then put on low for about 40 minutes. Any less time and then are not done.
Different beans take less time; pintos seem to take the longest. Soaking is essential. I use a lot of quicker cooking legumes like split peas, lentils and mung beans. I soak them all, esp. the mung (24 hours).
If you look into it you will see that the soaking isn’t necessary, in fact that is how I cooked a batch of beans so quick that I didn’t get to add the salt until they were almost done.
I put them my pressure cooker, fired it up, and after it came to a boil and high pressure, I turned it off to let them (quick) soak for a few minutes, when I remembered them later, they were either cooked, or almost cooked.
Pre-soaking can save time, but isn’t needed.
People should also remember using their coffee thermos for cooking foods like wheat berries, it works on many things.
You didn’t mention salt so I guess that like me, you salt your beans before cooking, there is a myth that one shouldn’t salt before they are soft.
I timed my beans tonight.
I brought them to a high pressure whistle, and cooked for ten minutes, turned off the burner and then let them sit for 90 minutes, this was with no presoak and salt added. My beans were almost done, they were plenty edible but not quite perfect, 15 minutes would have been better.
With a presoak, they should not need much time at all.
This is useful for cooking over an open fire because you can build a fire for the beans with minimal fuel, and still have plenty of fire left over for cooking other items from the left over flames and coals.
I sure beats needing a full 90 to 120 minutes of careful simmering, it saves water also.