We tried a prong collar the 1st time with Bava this weekend, and it made no difference whatsoever. I wanted to use it for his Petsmart visit where he feels the need to visit with every single person in the store. I had removed 3 of the links so that it was not loose, but it looks like he was wearing it too low. He pulled like the dickens to try and visit people, as usual. I did fit the collar with the rubber tips. I bought the collar because I thought it would be easier on his trachea than a regular band, and was more worried about him injuring himself with the prong collar, but apparently I didn't have it positioned high enough for a proper correction.
Anyways, I found a really informative page on how to properly fit the collar on your dog and wanted to share it:
http://shelzy.8m.com/prongfyi.htm