Over pressure problem with .223 Rem. or just a coincidence?

Seems I read similar post. Did you get your OAL srtaight from putting a sized case with slightly crimped long OAL bolted in the chamber then back off a hair?
As far as pierced primer. Did those rounds bolt in with more pressure to lock the bolt?

Change primers.https://www.accurateshooter.com/technical-articles/primers-and-pressure-analysis/

Is your brass all of the same date/headstamp/lot? I had an unexplained pierced primer in my 5.56 heavy long line load. Have fired thousands with no issues. Careful inspection revealed a WCC military case that had snuck into my Nosler brass. It was significantly heavier, and presumably had a lower internal capacity/higher pressure. I also found LC-11 with the stabbed crimps to have some heavy outliers.

Your load SHOULD be Kosher, but what your describing certainly sounds like overpressure. Check components and weights carefully. Another possible cause could be excessive heat by cooking a round in a hot chamber for awhile.

Try a different primer,Rem 7 1/2 or CCI #41.

Are all the LC the same Lot?

You may want to check if the ones piercing the primers have less volume.

No, it is not a coincidence.

You're only 0.3 grains below Hornady's maximum. They used Wincester cases, and you're using LC, which probably have a smaller internal volume. That's easy enough for you to compare with a water weight test.

They also used Winchester primers.

These two changes alone mean that you're shooting a load that's different from Hornady's.

The 23.3 max load worked in their gun under their test conditions and environmental variables.

Your circumstances probably necessitate a lower safe charge weight than what Hornady observed.

Why would the OP need to change primers? The ammo is being shot in a bolt action rifle, no floating firing pin to be concerned about there.

It sounds like an overcharge. Do not ignore a pierced primer, that is showing extremely high pressures. It's possible the 4895 is bridging in your powder measure and that round received an overcharge.

If you are not looking into each case after you throw the powder you should from now on. You might catch the next overcharge that way.

Which powder measure are you using? Ever send that ammo over a chrono?

ArchAngelCD said:

Why would the OP need to change primers?

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CCI 400 primer cups are thin. Do not use them with heavy loads

243winxb said:

Change primers.https://www.accurateshooter.com/technical-articles/primers-and-pressure-analysis/

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What @243winxb said

Hodgdon uses Win Primers and a higher powder charge. Yes a different bullet but the same weight.

The Article form accurate shooter is from 1995
Think primers may have slightly changed since then??

Rule3 said:

The Article form accurate shooter is from 1995
Think primers may have slightly changed since then??

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No. I posted before-

The CCI 400 primer flows sooner then Rem 7 1/2 for me. More so with 68/69 gr bullets.

Used 4 different burn rate IMR powders to work up loads. The CCI started flowing around mid-range loads when working up.

I put the Rem 6 1/2 & CCI 400 in the same class. Good for 40,000 PSI maximum. IMO.

Savage Axis now has 2417 rounds fired. Time for a new one.

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https://www.thehighroad.org/index.php?threads/blanked-my-first-primer.854168/page-2#post-11193687

Maxinum loadings add to the problem.

crest117 said:

I think I just pushed things a little too close to the max.

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Hodgdon's load data lists a maximum of 22.6gr of H4895 for a 77gr Sierra HPBT.
http://www.hodgdonreloading.com/data/rifle

crest117 said:

Also, should I shorten my OAL to 2.250 or is 2.260 acceptable? Will shortening the OAL slightly reduce pressure?

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Ten thousandths doesn't make a significant difference in terms of pressure in this case. However, shorter OAL's mean increased pressure. In this case, you want the OAL to first fit the mag without binding. Secondly, you might adjust for accuracy purposes.

You will have to consider the LC brass factor when considering published load data. Most load data is worked up with commercial brass.

The other thing to consider is ambient temperature. More heat means additional pressure.

Back off on the powder charge, and see what happens...

Nature Boy said:

CCI 400 primer cups are thin. Do not use them with heavy loads

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I don't want to sound combative but where did you hear that? I never heard CCI primers were thin. I have used many CCI-400 primers in .223 ammo meant for my Howa 1500 bolt action rifle and in some AR ammo too. I never saw a problem with CCI primers.

ArchAngelCD said:

I don't want to sound combative but where did you hear that? I never heard CCI primers were thin. I have used many CCI-400 primers in .223 ammo meant for my Howa 1500 bolt action rifle and in some AR ammo too. I never saw a problem with CCI primers.

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You aren’t being combative.

It was in the link that @243winxb posted

https://www.accurateshooter.com/technical-articles/primers-and-pressure-analysis/

I ran into this exact issue a few weeks ago

https://www.thehighroad.org/index.php?threads/blanked-my-first-primer.854168/

Like most things it’s never one thing.

Thin cup primer + hot load + slop between firing pin and hole + weak spring, or a combination of those = pierced primer

Do a forum search for “pierced” or “blanked” primers. You’ll see it’s mostly either CCI400 or WSR, by a large margin

ArchAngelCD said:

I never heard CCI primers were thin. I have used many CCI-400 primers in .223 ammo meant for my Howa 1500 bolt action rifle and in some AR ammo too. I never saw a problem with CCI primers.

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CCI primers aren't thin in general. Compared to some small rifle primers, though, their 400's are not super strong. That's part of why CCI makes their #41 primers - harder cupped SRP's for use in floating-firing-pin semi-autos

As Nature Boy points out, whether 400's are an issue in a particular application depends on a lot of factors. Before I learned of the existence of the 41's, I used 400's... also without issue.

ATLDave said:

CCI primers aren't thin in general. Compared to some small rifle primers, though, their 400's are not super strong. That's part of why CCI makes their #41 primers - harder cupped SRP's for use in floating-firing-pin semi-autos

As Nature Boy points out, whether 400's are an issue in a particular application depends on a lot of factors. Before I learned of the existence of the 41's, I used 400's... also without issue.

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I have used the 400s too but went to the 450s well before I learned of the existence of the #41 primers.

I found a significant difference in the hardness of CCI 400 vs Rem 7-1/2.

CCI looked flat and the Rem was perfect.

This was for The AR

JCSC said:

I found a significant difference in the hardness of CCI 400 vs Rem 7-1/2.

CCI looked flat and the Rem was perfect.

This was for The AR

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That is an unfair comparison, the Rem 7 1/2 primers should be compared with CCI 450 primers and you will see no real difference. The Rem 7 1/2 primers are labeled Bench Rest primers and are magnum class. The Rem 6 1/2 primers are low pressure SRP.