Thread: Brass life...

Originally Posted by zimmer

If when you lift the bolt it is tight all the way the issue is an over length problem, but it sounds like you have good control of your lengths sizing ie 2 thou bump.
If when you lift the bolt it is relatively easy up to the point when you reach the primary extraction cam and then there is a "click" this is a sign of a tight base.

Unfortunately, some dies just won't size that last bit above the base sufficiently once it has expanded over many firings.
I have found this with the 308 and had to borrow a mate's small base die. I think small base dies may only be made in 6mm BR and 308.

If you have some new brass measure above the base and compare with your 14x cases.

I recently posted a link to Alex Wheelers "click" test video for expanded and tight base brass.

How do you determine your 2 thou bump?

Bolt lift is fine it's when pulling the bolt back. My new batch of brass has 2 firings on it with zero issues. Both are Bumped to the same dimension.

The strange thing case head on the newer batch measures the same as the old batch both in fired and sized form.

I did just measure my case length on my old batch and they are over lenghg but this wouldn't give extraction issues?

Shoulder bump is measured with a bushing a machined to sit just inside the shoulder radius. Gives me a datum to measure from.


I'm not too stressed about throwing the old batch would be cool to know where the issue is coming from

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Originally Posted by Ben_welder

Bolt lift is fine it's when pulling the bolt back. My new batch of brass has 2 firings on it with zero issues. Both are Bumped to the same dimension.


I did just measure my case length on my old batch and they are over lenghg but this wouldn't give extraction issues?


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Try the black marker pen method to determine where the tight spot are.
Four stripes spaced around the case, top to bottom.

When you say overlength, by how much? This can create another more serious issue ie projectile pinch and very high initial pressure.