Fire formed cases

[DesertDug]

I am newer to precision reloading. I have always just sized my cases and checked them with a Wilson cartridge case gauge.

i now have the hornady chamber gauge and am finding some unexpected results when measuring my fire formed brass.

All brass was sized the same and fired with same load, trim length and powder charge. Which that said, I would expect that all the cases would measure the same. Is this a correct assumption? Where the case not sized correctly? Some where tighter then others when closing the bolt it all fit the Wilson case gauge. Maybe I am not setting up the full length sizing die correctly.

What shoulder should I be resizing to to get the .002" bump if this difference in formed length is expected?

Any advise in getting to this next level of reloaded would be great.

2.047" being the most common lenght
https://i.postimg.cc/6Q5Z0bfb/IMG-1808.jpg (https://postimg.cc/k2zDMcZW)

[CFJunkie]

Before you jump off the deep end, did you consider that you just may have measured how consistently the cases had been annealed?
It looks like a slightly skewed normal distribution that you would expect from materials variations.

[DesertDug]

Never would have know to consider it. These cases are not annealed. Am I...into the wind?

[CFJunkie]

DesertDug,
I'm sure they were annealed some time, probably not recently.
The brass necks normally react differently when fired based on how brittle the brass has become during use.
Annealing softens the brass, sort of a reset.

I would expect some variance in brass after some use, even within the same lot.

By the way, if you save some of your messages and clear your storage, I have an answer to the message you sent me that I tried to send you.

[DesertDug]

Done. Why of course annealed from factory load, these are Winchester .270 cases, did not think of that!

[varget204]

you need to get a Headspace gage,so you can measure it on your cases.Once you know that measurement,you can adjust your resizing die .001 to.002 ,you want to Bump Shoulder back .001-.002,so cases will fit your chamber.That way you will not Over work your brass.Once cases are resized ,trim the cases,{should be with in .001-- no more than .002 difference in length}Highly recommend you get a Bullet Comparator,[about $15-30] depending on brand.You can measure the Ogive of the bullet,you want to measure from Base of Case to Start of Lands and Grooves in your chamber. BTO base to ogive,once you determine what that measurement is,you determine what distance from L & Grooves to seat your bullets, LOOK UP BERGERS recommendations for finding Seating Depth,You should Always seat your bullets to BTO,not OAL over all length.with correct headspace,and measuring Ogive, your seated rounds should be real close to the same length.BTO length will give you the most accurate shells .