TM Glock 18c issue

[broklebean]

Hi guys I have above pistol. It's a GBB and when you fire it after about the fourth BB has gone the fifth BB kind of just drops out the end of the pistol. The mag has no leaks and is fully filled and the BB's I'm using are .2 any ideas what it problem could be or any ideas of fixing?

Thanks in advance

[broklebean]

All sorted just need a bit of lube