Sorry, I should have been more clear about the picky part. When I say picky I don't mean accuracy wise, I mean what it will fire. It will gladly accept premium Hornady, Winchester and Federal. However if I go to use something cheep such as American Eagle Tactical or Norinco 5.56 it will have multiple failure to fire's. There will be a dent in the primer but it doesn't go off. I have brought it to an experienced gunsmith and even he can't really figure out what it causing it.
Mitch
Edit: I should also mention that this is like 5 rounds per 20 and that the "dud's" ran fine in a different gun.
The SL-8 / G36 operates on a "direct" firing pin system. So , when bolt is in battery, the firing pin is resting on the back of of the primer
If you are getting light primer strikes, then you should first check if the pin is moving freely, and so what the maximum protrusion is when you push it all the way in by hand
I can measure for you later what the protrusion should be. I good guesstimate is the protrusion is at least the diameter of the firing pin hole ( just looked on 2 carrier assemblies in my pile of stuff )
I would guess that is where your problem is ( debris causing it not to extend fully in the bolt , tip broken off etc )
A bad hammer spring is also possibility but unlikely . The SL-8 / G36 hammer spring is pretty stout ! Secondly, it doesn't take much to fire off primer if your protrusion is correct. The big exception is if anyone took the FCG apart. It is easy to assemble incorrectly.
If your firing pin protrusion is ok then check right side hammer spring to see if its installed correctly.
The LHS hammer spring rests under the front pin
The right side of the spring tail is gainst the front plastic wall of the housing. Common mistake is the RHS spring rests on the front pin like the LHS ( go figure its not symmetrical ! ) . Result is less hammer spring tension
My SL-8 and by buddies both fire 100% reliable all ammo