Problems with shooting my P08

[Brodie]

I have problems with my Luger and that is when put 5 rounds in my mag the first round fires but the next one (the fourth round)
gets stuck between the Breechlock. See photo.





But if i put four rounds in it i don't have this problem.

I think its the spring of the mag but if i use a othe mag i the problem to but not every time.

Can some help with this?