g37 help post for friend

ok recently purchased glock 37 ,bud of mine got one too, question is when you shake his pistol it seems the slide on the rails is alittle play in it? is that normal ,its his first glock ,and my 3rd . so i dunno what to tell him ,i mean not to serious to me but if you hold gun and shake it side to side ,it makes asound, and like i said i took apart for him and put back together and it still has alittle play in it. should he send it to glock ,or is that normal ..






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