I had the same issue with my Wintec 500 AP. I switched saddles (Stübben Scandica DL) and no more issues whatsoever. My horse never acted sore or uncomfortable in the Wintec but I definitely noticed a difference with the saddle switch.
I have the same problem... And I also think its a saddle fitting problem...
I´m getting a custom saddle right now...
Actually Bryan, the Voltaire rep who came to our barn yesterday, said it is a very common problem. They worked on it and developed a new saddle especially for ponies and I have to say the fit was pretty good! Kids at our barn were pretty excited that they got to try the first US prototype, Bryan said they haven't even found a name for it yet. I'm not sure how long it will be until they officially launch it but it seemed very promising... It was high time a French brand starts developing a real pony saddle as opposed to just making a smaller version of their full size saddle. It's pretty obvious that ponies aren't built like miniature sized horses...
Nike13, cruppers are legal in dressage. I ride my Arab in one. As someone else pointed out, it's a cheap fix for a frustrating problem, and if your pony already accepts it, you're a step ahead. If they are correctly fitted, they don't affect performance in the least.
To share my similar story, I tried a bunch on saddles on my guy and every single one slid forward. Everything. I tried the girth thing, the pad thing, spent more money than I'd care to recall shipping saddles, and nothing worked. In desperation, I figured he'd need to wear a crupper if I taught him to drive, and it solved the problem such that I was able to use a saddle already sitting in my tack room.
Another thought is that an 18" girth is really short. I had better luck with a longer girth. Not sure why.
Ginger, did a longer girth help with the sliding forward, or do you mean it was just easier to find?
She has decent withers, and side-to-side slipage is not a problem. Fortunately she is very accepting of the crupper, so hopefully that will help. Up until now, I've just used it when riding steep hills/long distances.
Here's hoping a short anatomic girth does the trick. A custom saddle is not in the budget right now, and even if it were, who wants to ride over the river, throught he woods, and into a briar patch in something that expensive? I'd probably break down a cry the first time I scratched it.
Nike13, the longer girth helped stabilize everything and did help somewhat with the sliding forward, although it didn't cure the problem. However, I do use a longer girth now with the crupper. It's also a heck of a lot easier to adjust from the saddle. If a very short girth won't solve the sliding forward, those buckles will be hitting pony's elbows, so do keep an eye out for that.
You might try a Thorowgood Griffin or the more modern t4. They have very flat
panels and are made for round horses. I have two Griffins and also a Wintec Pro and a Wintec AP both of which have adjustable gullets and neither of the Wintecs fits my little round 13.2 pony as well as the Thorowgood Griffins.