brass growth

[Texas Solo]

After the second firing, I'm getting a consistent .010" growth in my brass (LC 308) I'm not concerned about it, just wondering how much is normal.
I'm running a light load of IMR4064 and 168's. At what point, if ever, does the brass slow down or stop growing?
New to the 308 caliber.

[bootsmcguire]

Are you FL sizing, shoulder bumping, or neck sizing?

Whichever you are doing, what dies are you using?

[the Ranger]

are you trimming them? you will need to.

If you keep using the same sizing techniques the growth will be pretty consistent. the brass flows forward as a result of firing and resizing, the result is thinning of the case wall, mostly just above the head. this will continue until you get a "case head seperation".

you can reduce this effect by neck sizing only. or if you feel the need to full length size (a good idea in some cases), back the die off to size the case only as much as needed for reliable chambering.

[Texas Solo]

Are you FL sizing, shoulder bumping, or neck sizing?

Whichever you are doing, what dies are you using?

Full length sizing with std RCBS dies. I got the brass once fired, sized it, and trimmed to 2.005". After two firings, and trimming, it still grows to 2.215".

[scope eye]

Check your headspace, if it is loose it will cause brass growth.

Dean

[bootsmcguire]

Solo, are those numbers right? They grew from 2.005" to 2.215"?

That is a growth of .210", almost a 1/4 of an inch! If so something seems off to me.

[Handloader]

You running these in a self-loader? If so, your extraction pulse/timing may be off and extracting the spent case too soon (thereby "stretching" the case). If in an auto loader, the position of where the spent brass lands relative to the angle of the rifle can assist in the diagnosis of this.
Scope eye could be spot on with issues in headspace for either a semi-automatic or in a Bolt or single shot.

If these are only fired from a Bolt or single shot, you may be pushing the shoulder too far back when sizing.

[Texas Solo]

Solo, are those numbers right? They grew from 2.005" to 2.215"?

That is a growth of .210", almost a 1/4 of an inch! If so something seems off to me.


TYPO !!!!! growing to 2.015.....010" that's ten thousandths for those of us with finger dyslexia.

Rifle is a new #12BVSS. I seriously doubt a headspace issue, but I will check anyway.

So what you're all saying is that .010" growth is excessive?

[bootsmcguire]

My first thought is you either are sizing the brass back too far, or slightly loose headspace.

[Texas Solo]

OK, thanks Boots. I'll try backing off the die 1/8" turn. It's now set so that it just barely cams over when the ram is raised all the way against the shell holder (no brass installed)