Classic small spring out the guide rod hole. The ridge was barely detectable and didn't seem to surround the hole completely. Embarassing situation too. Was shooting with friends, one asked to try a mag through it and the spring popped out on his first shot. You can imagine the heehaws. So I guess I will call Kel-Tec tomorrow and try not to be a total a****** about it. > I thought there would be more of a ridge, had planned on getting the washer put in to stop it. Guess not now! Have to say the gun has been running good, it was right at 150 rds. when the SHTF.