I may be wrong with the type of collar you are talking about but I'm assuming you mean a lead collar with a barb, correct? There are ring and barb collars that have a ring in order to hold and flare a skirt, then there are the plain collars that just taper down from the head and have a barb at the end, and then you have your holder barb which is like what is on an Ultra Minnow jig. The plain tapered collar with a barb is made to not split plastic, the taper allows a smaller entry point and gradually widens , this also helps the barb hold by creating a wedge effect. The holder type like the ultra minnow jig has is there to be able to hold plastic as well as to provide flare for some type of skirt or dressing, it tends to be a little short but it holds plastic fine unless you get it hung or catch a fish and that is when it usually gets pulled off. The ring and barb is the same as the tapered collar but if used without a skirt or dressing it holds a bit tighter due to the collar but they also tend to tear the plastic a bit after a few fish. If you are using a tapered collar and you are splitting the plastic, perhaps the plastic is too small for the jig or I'm not understanding correctly but a tapered collar works well for me.