Theobe Gas Ram Stronger Front Cocking Arm. I have never had one break.
Replaces the thin plates that are standard and can break as it seems that one is taking the load, and being thin breaks. This is a common failure.

Check the dimensions on the second photo to make sure you have the right length.

But if you do have a different length or different gun then I can probably make a different size to suit most guns.
I alo have quick detachable pivot pins for the front and a shorter one for the middle link.
The last photo shows the short one that is around 10mm while the longer one has an 18mm length for the wider breech pivot. Just remove the small circlip and pull out without the use of a punch and hammer. 
The ones that need the punch can very often work themselves out and cut a groove through the underside of the stock, or fall out.