1937 Mauser Luger (S/42)

[Galaxy88]

I just picked up my first Luger and took it to the range today. This is a great looking piece of art-but I had an issue. Every second or third round fired, would not fire(click). The round stayed in the chamber and I had to physically remove it. I examined the round and it looked to have a lite strike on the primer. Could this be the firing pin spring?? Thanks!