[Sydwaiz]

This one has a shoulder on it. Also, the notches are slightly smaller than the raised portions on the movable catch so the two parts don't sit flush together. Is this an early model? I've never seen one with a shoulder on it.

 

[Lucky#13]

My impression was that the ones with the shoulder for the spring were the later style. I could be wrong!

 

[Sydwaiz]

I'm just going by the TM on Liberators site. It shows the shoulder in the drawing of the A6.