Resizing question

[Big Dunc]

Hey all,

I still consider myself fairly new to reloading (~4 years). I’ve seen this line on my brass after resizing and was wanting to get your thoughts on what is causing it and if it’s an issue. I have a few friends that I go to for reloading questions but they are split with the answers. RCBS full length die, Hornady brass (have also noticed it on my Lapua and Norma brass in a different caliber).

 

[doverpack12]

Is the line there before you size?
Looks like a rebated rim case, to me the die is sizing a spot on the brass where the solid base ends and is making that line from the effort.
Measure that spot before and after sizing to see what is happening.

 

[Mag_7s]

Almost looks like the beginnings case head separation. Do you have a shoulder datum comparator tool to measure how much you are setting the brass back compared to your chamber dimensions?

 

[packer58]

Does all your brass look like that or just random pieces ?

 

[Bluefish]

Could be impending case head separation or just where the sizing die stops. Sizing die doesn’t go all the way down the case.

to check for case head stretch, take a sharpened paper clip that looks like a L and run it along the inside of the case. You should feel a ridge/valley if you are having case head issues. if it’s case head stretch, scrap the brass.

 

[EdP]

Some info on signs that a case is in imminent danger of head separation.

The line is usually brighter than the surrounding brass and very sharp. Your line is very sharp but appears darker than the surrounding brass. A check of the inside either with a scope as in the 1st video or a feeler gauge as in the 2nd may sort it out for you.

 

[11boo]

What EdP says.

A paper clip makes into a decent feeler gauge.

 

[BBob]

All brass is going to eventually show a mark at the ~.120” line from the base. As others have suggested check the case for separation. If it’s it’s not carry on

 

[Big Dunc]

Does all your brass look like that or just random pieces ?

Random pieces. And I have noticed it in other calibers as well.

 

[Big Dunc]

Some info on signs that a case is in imminent danger of head separation.

The line is usually brighter than the surrounding brass and very sharp. Your line is very sharp but appears darker than the surrounding brass. A check of the inside either with a scope as in the 1st video or a feeler gauge as in the 2nd may sort it out for you.

Thanks for these. Mine don’t seem to be very sharp when looking up close

 

[Big Dunc]

Could be impending case head separation or just where the sizing die stops. Sizing die doesn’t go all the way down the case.

to check for case head stretch, take a sharpened paper clip that looks like a L and run it along the inside of the case. You should feel a ridge/valley if you are having case head issues. if it’s case head stretch, scrap the brass.

Thanks for this. I think it’s just where the die stops. These are brass that have only been once fired.

 

[EdP]

In the 2nd video I sent you can see the ring where the die stops below the ring where the case is beginning to separate. That view was especially helpfull to me in seeing the difference between the two.

 

[Harvey_NW]

If that line is just leftover wax from the sizing die, completely normal. Wipe or tumble the case clean and roll on. Never hurts to check it with a paper clip like the videos show.

How are you setting up your sizing die? Are you using a comparator and bump gauges to measure at the datum and properly bump the shoulders back, or are you smashing it back to SAAMI dimension like the Neanderthals in the RCBS and Hornady reloading videos tell you to do?