Leaving legalities aside, the round traps ain't got the same power, as BMI, Belisle etc. But it's more that dalm trigger mechanism. One notch, that can be hard set, or keep set, and then, it never seems to sit right. Always seems to lie somewhat in or out. Yea I'm sure you can modify to improve, but you shouldn't have to do that.
On a plus side, yea they fit nicely inside a pipe. A pipe makes an excellent tunnel. So it gets a thumbs up for that aspect.