I've been using that same snaffle since day one - about a year and a half. A month or so ago, maybe six weeks, Izzy started to be a bit of a stinker about taking the bit when bridling. Gradually, it got to the point where he flat out refused to open his mouth at all.
That should have been a huge red flag for me, but he had taken that bit eagerly for so long that I assumed he was just trying to get the upper hand in a power struggle. I was wrong.
I still haven't made the switch to the double bridle. There's a problem with the bradoon hanger which is a long story and completely my fault. Either way, I can't show with either bit set up. The correction bit is definitely not show legal, and I can't show below Third Level with the double. I'm going to need to find a snaffle that works if we are to get back in the show ring this spring.
When I compared the two bits, the first thing I noticed was that the correction bit allows tongue relief while the snaffle does not. It restricts the tongue and collapses on the bars of his mouth. The center lozenge puts concentrated pressure on the tongue. Is that what bothered him with the lozenge snaffle, the lack of tongue relief?
According to the 2016 USEF rule book, a double jointed bit or snaffle with rotating mouthpiece may be shaped to allow tongue relief. The maximum height of the deviation is 30mm from the lower part of tongue side to the highest part of the deviation. The widest part of the deviation must be where the mouthpiece contacts the tongue and must have a minimum width of 30 mm.
If you have one for sale, let me know!