[HairOfTheDog]

My DIL is running her horse in a mechanical hack. But she uses a tie down.

It wasn't so much out of discrimination against tie downs, I'd have just thought it might interfere.

[FrogInABlender]

...I'd have just thought it might interfere...

Me too. At one time, I tried a mechanical hackamore with my trail bridle on Tennessee and it kept getting stuck on the nose band of the halter part so I just switched back to a regular curb.