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CZ457 Lilja barrel headspace

Set headspace at .043". It's what CIP and SAAMI specs call for. Setting it to something else isn't a shortcut to better performance.
 
Probably correct but like lot testing too many variables in the 22LR world...if you have the time and patience start at .043 with your preferred lot and go plus/minus a few thou on the shims after establishing a solid baseline. Might improve, might be a waste of time...never a waste of time once you go down the rabbit hole, just the satisfaction of proving yourself right or wrong, it's all good. Keep us posted on your results, enjoy.
 
My first attempt many moons ago was at .041. I was having extraction issues. Went to .043 and everything was golden. No issues with Eley or SK/ Lapua. That rifle has been flawless to this day.

They do provide shim kits for a reason, and I’m assuming tolerance variations.
 
For those that have made this upgrade, what did you set your heads pace at and how well did it work?
Headspacing has been proven to have little effect on accuracy until you reach the point of inconsistent ignition or hard bolt closure. .043 is a good number and generally works for both Lapua and Eley. But not always! Eley has a thinner rim than Lapua. It's possible to have good ignition with Lapua but occasional FTFs with Eley. On the other hand, headspace for Eley alone and you'll more than likely have hard bolt closure with Lapua. I have had guns that I was never able to set headspacing to shoot both brands of ammo reliably.. Probably due to inconsistent bolt lockup. This is where blueprinting a receiver comes in play!
 
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