OzFclass

my son has a omark in 5.56mm

having the odd extraction problems, have checked the load, case length , full sized etc etc

1 thing i have noticed is that , if u push the bolt handle forwards whilst lifting, cases will extract no problemo

so any bright ideas on improving etc

You have insufficient primary extraction. Pushing the bolt handle forward gives you that few thou extra of primary extraction--just enough to get the cases out.
Solution1,
Have someone competent remove the bolt handle and re solder to the tube about 1mm forward of existing position.
Solution2,
Send me the bolt tube only and I will fit a hardened steel insert giving you about 1mm more primary extraction.
Barry.

Ozfarm,
A mate of mine has a Omark with the same trouble, the trouble was the gap between the bolt face and the hook on the extractor, The gap was opened about .010 and the extractor can now slip over the rim of the
223 case no worries.

hope this helps

Update:

barry davies modified the bolt handle in the way described & everything is working hunky dory