I have a wonderful gelding that is running decent times for as long as we have been running but we have hit platue. I believe he looses power in his turns because he is too bendy in neck. I tried a stabile bit with Mullen mouth and loved the turns but he had no stop :/ very odd I thought! He stops beautiful with simplity bit which isn't much more than o ring. Any thoughts? Help or advice?

I have a gelding that sounds just like yours!! I run him in a mullen also, and have noticed that he doesn't stop as well. But for our runs, I started squaring up his turns more and that pretty much solved him over bending around the barrels =] Hope this helps!!

Unless he is dangerous with less of a stop,  I wouldnt sweat it. If your getting the results in the pattern then your good to go, thats where you win paychecks. I would ride in the regular bit for day to day and only put the mullen on during a competition run. 

The ‘squaring up’ really does help. I think you may need to get true bend in him. Meaning from the rib cage and neck. Too many get the neck, but not the rib cage. This is in everyday arena riding. If you get too much neck, not enough body/rib cage, he will eventually start to ‘flip his a$$’ around a barrel with more speed and really lose time. There won’t be drive in the turn. 

I hope that all makes sense the way I explained it.

I can do it, just sometimes difficult explaining. LOL

He doesn't swing his tail out and we are running 3d at super shows but I do know he loses power leaving.  I will work on the squaring exercise too. I am sure part of it is me. I am a grandma still trying to do this stuff :) so not having breaks is not an option. I really am just shocked that going from simplity with super loos curb to a million mouth with 2 finger curb we lost breaks. :/ I am gonna try something with less gag but twisted wire and see what we can get I guess. Thank you for the replys.:)

I’m not saying he is swinging the tail now, but he will if you don’t get that tail driving with more speed.

You will be fine. Just take your time. You seem to understand what you need.

Thank you :) part of me is scared to Jack with too much because I am super blessed to have him going this well. I just know we could get a little more. :)

My horse is like a little noodle. I switched her to a hackamore and it helped a ton. I just use a beetle hack, but I know they makes ones with more stop. 

Check soreness too. I had a gelding that had to much bend. After I did some drills and changed bits it didn't improve. I headed to the vet.He ended up being very sore in his stifles. Injected and he was instantly better the following week.