I used to have a ton of trouble with these tails (although mine was the 2.5 inch swim fry). I whined and moaned on this site for days on end and finally gave up. The answer came to me when I was trying to shoot a jacobs 2 inch curly tail bait and had trouble with the tails forming. When I looked at the mold I noticed the runner was extremely narrow and the plastic was cooling before it could get all the way into the tails. So I shot it hard and fast and it worked. Sooo I went digging thru my stuff for the swim fry mold. Would it work? Yep. Shot her hard and everything filled in fine. These are pretty much the only molds I use this technique on but it works for me.