Depending on which 4" Grub mold it is it could have been by Chris at Ultra Molds. It should have a model identification on the mold. I have 5 of the 4" Curly Tails that I bought from Dave and Ultra Molds is still producing this mold.
The best that I can remember, back in the day when I bought my tube molds, they were about $65.00 to $85.00 each, depending on the size. Now they are $108.50 to 129.50 ,depending on the size, for the same molds.
I talked to them about a month ago. The site went down and they decided not to put it back up. They are still in business, you can give them a call and they will take your order over the phone.
This is the best way that I have found. Put them in a plastic sandwich bag and vigorously rub them between your hands. This will create static electricity that will cause the strands to seperate.
The molds that Bear sold were made by Ultramold. They are available on their web-site. Do-It and Enforcer Molds also have splined molds. I am only familiar with the Ultramold tube molds, I have about 25 of them and they are very good molds.
Proberos Fishing. He is in China but they are reliable and the shipping is pretty fast. They also have an Ebay store. I bought 100 of the wires from them, the wires are about an inch longer than VMC, maybe not quiet as heavy, but they worked fine for me.
I agree, the gate is the area where the plastic first enters the bait cavity. It has been my experience over the past 15 years of injecting that if it is a dent problem it is because the gates are too small, if it is a filling problem it is usually venting. I am not saying that temperature or clamp pressure can't play a part, but I feel if they do it is usually because of design to start with.
I doubt that most of the folks that have only been injecting plastic for a few years are aware that Dave is one of the early driving forces that has made injecting what it is today. God bless him and his family.