I've got an ICS Sig 551 that has a plastic folding stock. The first time I took it out last summer I noticed that if I fold the stock the whole thing splits along the center seam both top and bottom when I unhook it from the rifle body. Basically I can lightly twist the stock side to side to expose the seam. The stock itself is still solid to the rifle body but I've tried sealing the gap with Krazy glue and recently with JB Weld and neither one worked so I'm up for suggestions for my next step.
Here are some pictures for reference