I just got into the sport and started with a Glock 19. I really enjoy the gun, but when I put in the magazine - with or without bullets - I feel as if the magazine isn't held tight. There's about a 1/8" gap from the foot of the magazine to the bottom of the handgrip. I can push the magazine up, but it comes back down. It just feels 'loose'. Is this normal? Should there be some play? If this isn't correct, how do I rectify this? I bought the gun brand new, so it's not an issue of a previous user. Thanks for your insight!