I have a large & mini Hot glue gun and a small warm melt glue gun. At a craft show, a vendor was gluing with NO strings. I watched him for quite awhile, then asked what brand his hot glue gun was. He said the brand did not matter as most people do not let their gun get hot enough before using it which is why you get strings.
I now let mine heat up for a long time before trying to use it. You will get glue running out and feel like you are wasting glue but there will be less or NO strings when using it.
Before buying a new gun, try this first.