Winchester M70 Bolt Question

[AZ_Rebel]

Looking at a bolt for a .222 Rifle that had a small "lever" on the front just under the bolt face. kind of looks like an extractor but has no hook (and the bolt has a Claw Extractor). The lever is held in with a pin and sits next to the groove that the ejector rides up and into.
Does anyone know what this is and what function it performs?
Thank You!

 

[hksw]

Is it the Gas Block part number 22 for the Control Feed M70?

(Exploded view, warning - large *.pdf file)
http://media.winchesterguns.com/pdf/parts/2008_winchester_parts_pricelist.pdf

 

[AZ_Rebel]

Yes, I think you are correct. It looks like the part and it is on the correct part of the bolt in the diagram. But what does it do?
Also, the diagram does not show the pin and a spring that was underneath it. I am still puzzled somewhat.
Thank You!

 

[hksw]

I do not have a control feed M70 but would hazard to guess that it covers the ejector groove when the bolt is turned down to prevent any gas from venting backwards towards the shooter's face in the event the case ruptures during shooting.