Disappointed - Tacfire Mossberg 500 Shotgun Pistol Grip

I put this on my mossberg 500 and finally for the first time in weeks I was able to get out and shoot with it for the first time. Not too impressed. The stock itself works fine, but after my 3rd shot, the cylinders under the cheek rest slid out! I couldn’t believe it. So I reset them and fired once more, and sure enough they slid out. I ended up removing them, I suppose it is just a cosmetic aspect that malfunctioned but I’m still upset about it. Also comes without any directions, luckily I’m handy enough to have figured it out. Good luck.