Yep, that’s it.
No locked breech means it kicks harder than it should for such an anemic cartridge, trigger is hard as a rock, sights are virtually non-existent. Mine is the true 9x21. Ammo used to be (maybe still is) plentiful.
Obviously mine has sentimental value and won’t be sold, but I have seen many of them at gun shows for $150 and less. The guy wanting $375 is probably an optimist. Mine actually came with a holster, but it started growing mold and was discarded decades ago.
On the link, that is an auction site where you can see what the guns actually sold for. $350 is not unusual for one in good condition.
Sorry to hear that yours has a hard trigger. Mine have had very good triggers. The cartridge is a bit more powerful than a standard 9x19, in between it and a .38 Super.
The machining on those pistols would make them $1000 guns today. Pretty tight tolerances and significant machining.
The sights are fixed, and they are small. They are no smaller than the Colt 1911 sights made in the same period.
Certainly a collectors gun today. If I would see one for $150, I would grab it in a second. The original box and shipping information makes it even more valuable.