Brass Question: Headspace grows after bullet seating.

[trailtundra]

I loaded a few hundred 223 using twice-fired Lake City Brass and 55gn Hornady FMJBTw/C and there were six rounds that had a little resistance when seating the bullets. I checked them in the case gauge and they were long. Then checked the headspace with a caliper and the six rounds all grew by 5-10 thousandth.

I didn't notice anything when resizing (w/ redding small base). I'm wondering if this is what happens when the necks are work hardened and need annealing/are no longer serviceable? Anyone experience this?

[highpower790]

Are you trimming brass before or after sizing ?should trim after ...the reason being that on the down stroke the necks could be stretched.

[trailtundra]

Are you trimming brass before or after sizing ?should trim after ...the reason being that on the down stroke the necks could be stretched.

Trimmed after sizing. Also, the brass measures 1.750 +/- .0015. This problem isn't very widespread, just six cases in 300. Reloading these for the second time (third in their life) and I'm wondering if this 2% are just cases that gave out early. I also found one with a split neck after just two firings.

[OpenSightsOnly]

OP, are you sizing the cases using a progressive or single stage press?

[trailtundra]

OP, are you sizing the cases using a progressive or single stage press?

Single Stage. Redding T7 with Redding dies.

[JTROKS]

If you trim after sizing how the heck did 6 cases grow? Don't mind me I'm just thinking outloud.

[highpower790]

What brand of brass?Ive had issues with the necks splitting on Federal brass,so now its LC brass now.

[trailtundra]

If you trim after sizing how the heck did 6 cases grow? Don't mind me I'm just thinking outloud.

That's what I'm trying to figure out. I'm wondering if it's just cases that don't want to work anymore, or if I did something. It's an insignificant amount but it's so weird that I want to figure it out.

It's almost like the bullets are larger than .224 causing the necks to blow out larger than spec causing the increase in headspace. But I measured the necks of these weirdo rounds against others and they are the same at .2475 +/- .0005.

All brass is Lake City once fired by mil, and once fired by me. They are being loaded for the third time.

[OpenSightsOnly]

That's what I'm trying to figure out. I'm wondering if it's just cases that don't want to work anymore, or if I did something. It's an insignificant amount but it's so weird that I want to figure it out.

It's almost like the bullets are larger than .224 causing the necks to blow out larger than spec causing the increase in headspace. But I measured the necks of these weirdo rounds against others and they are the same at .2475 +/- .0005.

All brass is Lake City once fired by mil, and once fired by me. They are being loaded for the third time.

Do you have a cartridge headspace issue as in the full-sized brass will not fit the chamber?

OTOH, is the issue related to a brass that has a longer overall length after trimming?

If latter, what trimmer do you use? I used to have a Redding trimmer with the micrometer, a very good trimmer. However, the drawback is that I have to sort the sized brass to find the shortest of the lot then use that as the basis for the trim. Not anymore, I upgraded to a Giraud!

Perhaps, this is related to your trimmer set-up?

A stab in the dark

[Dark Mod]

this should not be happening. Its bizzare, the only problem i can think of after sizing is too much crimp.

If you overcrimp and buckle part of the case it may appear like to be a headspace issue.

Inspect dat brass and see if theres any buckles

[trailtundra]

I use a Forster trimmer.

The crimp idea make a lot of sense because of the resistance I felt when seating bullets in these particular cases. But it's just weird that 294 would seat normally without any issue and these six wouldn't. I have my die setup with very minimal taper crimp.

I don't know why I am so hung up on this. I appreciate all of the tips and input.
I pulled them apart and assembled three rounds using the bullets with other brass without issue.

After closer look, checkout how they kind of slightly mushroomed where the neck meets main part of the case.Like the necks were smashed down.
(Left case is ready to load from the same batch)

[God Bless America]

that can happen while seating if the die is not adjusted correctly.

won't happen with a lee FCD.

[2shotjoe]

Over crimp, brass is bad now. Save it for 300bo.

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[AeroEngi]

Seems like you're trying to crimp while seating the bullet. Back out the seating die a bit so it doesn't crimp.

[J-cat]

Over crimp, brass is bad now. Save it for 300bo.

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No it isn't.

Fun it through a FL die and it will be fine.