i have a new glock 17 gen 3 that the stock guide rod or an aftermarket stainless steel one will not stay down in the half circle cut in the barrel when the slide is worked by hand. i put it where it is supposed to be and work the slide and it is out again. i thought it was the stock guide rod hence i bought an after market one, has anyone had this issue? if anyone has an insight it would be greatly appreciated as i have been hesitant to fire it when the guide rod won't stay where it is supposed to be