308 brass has "step off" after sizing

[dumbkid]

Hi.

I keep my FAL and bolt action brass separate. After a couple times reloading my brass that I use in my FAL, some of the brass won't size all the way down and instead has a "step" at the bottom of the brass. It doesn't happen with all the brass, but it does in about 1 per 10. I tried sizing with two different dies to see if it would correct the issue, but it hasn't helped. For reference, the dies used were a LEE full length die and a RCBS small base die. Both had the same issues and occurrence.

Any idea how to fix this issue? Or is it mostly because the FAL is harder on the brass so the life isn't as long?

[fal_762x51]

Looks like case head separation is about to occur. Recycle brass immediately.

I usually only get 3-5 reloads on my FAL before I can see the bulge from the wall and the case head.

[ChrisGarrett]

That looks kind of dangerous, but why is it only doing it 10% of the time?

How many cycles on this brass, what headstamp? Is it doing it on one particular stamp?

Have you taken fired measurements of your brass near the case head and for headspace?

While not has heavy as my HK-91's BCG, my FN-FAL has a pretty massive BCG when compared to that of an AR-15, so that brass gets stretched out, especially if you're overly bumping your shoulders back.

Chris

[ChrisGarrett]

Looks like case head separation is about to occur. Recycle brass immediately.

I usually only get 3-5 reloads on my FAL before I can see the bulge from the wall and the case head.

It sure looks that way on its face, but that ring is a bit low for case head separation IMO. That ring is down near the bottom surface of the case, where the webbing is very thick and radiused.

Whatever it is, it doesn't look good, does it?

Chris

[bohoki]

you might need more lube or you have a slightly too generous of a chamber (still safe just slightly large)

that brass has met end of life

[dumbkid]

This group of brass has had about 2-3 cycles on this rifle.

I haven't checked the length of the brass prior to sizing, so that may be the issue. Maybe all the excess brass at the neck is compressing down and causing the excess brass at the bottom. I'll check that when I get back home. Thanks for the replies.

[KeithET]

Its kind hard to tell from the pictures what we are actually seeing. Is there an actual rim being created right there at that bright line near the base?

Some thoughts come to mind by looking at the pictures with out the benefit to actual handle the brass.

1. As mentioned earlier a generous chamber allowing the brass to expand a bit to much which makes resizing more difficult causing the bright rings and lines on the brass. This effect is just an indication that this brass is worn out.

2. Possible overpressure situation. As these have been reused a few times each time the web part of the head has expanded just a bit until you have this situation with a few of the cases. I have to ask another question for this one though since I can't tell from the pictures. Is the case body just in front of the extraction grove measurably larger then on cases that do not show this problem? You will need to use a micrometer to actually tell this for sure. With an over pressure situation your brass will expand not only the body that gets re-sized each time but also the web or solid portion of the head. With a mild over pressure situation you can re-load it a few times before you notice the web getting expanded.
If you loaded these rounds at or near max loads then that could explain this situation.

All of this is very hard to judge since we cannot actually closely examine the cases.

KeithET

[SandDiegoDuner]

What kind of press are you sizing these pieces of brass? I have seen that happen with some thin walled .40 s&w brass when the shell plate was not rotating all the way into position when resizing and enters the sizing die at an angle.

[chasjr1]

looks to me its just where the die stops on the brass, is you die adjusted all the way down and how much lube are you using ?

[russt]

When in doubt throw them out. A few pieces of brass aren't worth the risk.

[chim-chim7]

Overpressure. The sizing die is leaving a witness of the fired sized. Recycle now, revisit load data. Carry on.