Get your own sprayer. Not only will you avoid being back-doored like this situation, you can also save a whole bunch of money on the chemicals themselves. Plus you will know beyond a doubt that the chem you paid for is on the field.

It is another job to worry about. It is also a very, very good paying job.

To answer the original question, the only time I have ever had trouble with AMS is when I got sloppy and just dumped 2 bags of it in the tank. Plugged up the intake hose to the pump. Luckily, I wasn't in a great big hurry and was able to just let it sit for a day and it all dissolved. Have never had a tip plug that I would blame on AMS- atrazine is a different story but you didn't ask about that.