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Pressure? What Happened? 223 (long read)

Were these cases cleaned? Sometimes you can get a carbon buildup that causes reduced capacity in the case. You can also get dirt or grime in there that does the same. That is if the cases weren't cleaned.
If the cases were cleaned (in a tumbling media), some of that can get left in the case, again causing reduced capaciy. Shine a light in the empty cases making sure nothing is left in them.

That load and LC brass have never caused that issue for me. But, other brass has...due to lack of inspection on my part.
Yes , cleaned. They came to me cleaned. I full length resized and, checkd primer pockets/removed crimps, washed in weak soap solution (no pins) in a rotary tumbler for about 20 minutes to remove the lube. After dry, primed, then loaded.
 
I did see an old post from LVLAaron talking about leaving behind LC processed brass as an option, because the primer pockets were too often blown out.
 
Sounds like a bad piece of brass or a primer cup that didn't press into the pocket well. Something allowed a bleed off of gas that vented to your extractor. The chrono data is a pretty good indicator that there wasn't a pressure spike.
 
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That piece of brass may have experienced high pressure in the previous loading (expanding the primer pocket, but not failing) where pressure kept the primer in place. A loose primer will leak a lot of gas, as it generally won't seal properly. What is the history of this brass? Were you the only one to load it? Did any previous loads push the edge?
 
If it was .mil LC once fired, the pockets are swaged or reamed to remove the crimp, sounds to me like you got one with an oversized primer pocket and it allowed the pressure to vent, which is what got you the sting and damaged the bolt.

I don’t know how you prime, but as mentioned above hand priming will let you feel that.
 
i've been shooting 53 vmax at 3500-3600 (prob 55-60kpsi easy) out of my 223 for almost a decade now. the lapua brass i'm using currently has at least 10 firings on them, never an issue of any kind.

my n133 load is compressed, and i probably couldn't get enough of it in the case even if i tried really hard, to have any sort of catastrophic event occur. n133 is considerably faster than varget, so idk how you could come near the pressures to necessary to cause any sort of case failure.....i dont care how bad a carbon ring, or whatever else is.

all signs lead to a bad piece of brass IMO
 
Definitely a faulty case. Two possibilities:

If previously fired, damage from an overload. But you should have noticed that in resizing / priming. (Or possibly, but unlikely an incompetent annealing effort by the previous owner.)

If new, a 'soft' case possibly due to faulty factory annealing, or the brass alloy used. Such cases occasionally get through the factory QC process and the fault is only discovered in use, in which case the batch is recalled.

I saw this some 20, 25 years ago with a consignment of high-quality European 270 Win ammunition which the UK distributor had put a safety notice out on and given dealers refunds. A local dealer had around 1,000 stuck in his warehouse for years and as the distributor had gone out of business nobody knew what the fault was, or what to do with them. I cadged a couple of 20-ct cartons and tested them in an old Brno ZKK (an improved Mauser '98 type action, virtually indestructible). Nine shots were fine, got MVs from the load which were close to those stated by the maker, grouped well. Shot 10 went into the group, MV was within the range of its predecessors, but the bolt had to be forced open and the primer fell out on case extraction. Nothing wrong with the rifle, load, bullet - just a soft lower case-body and case-head which expanded mightily as much as the chamber allowed. Manufacturing fault, hence the distributor's withdrawal notice.
 
Seconds count has the answer. 223 Maximum case length is 1.760 and the OPs case was 1.759. This COULD mean that one case got missed in the case trimming process and when chambered the extra length of the case got pinched by the chamber and created an over pressure. I have seen it happen, and it isn't pretty.
 
Seconds count has the answer. 223 Maximum case length is 1.760 and the OPs case was 1.759. This COULD mean that one case got missed in the case trimming process and when chambered the extra length of the case got pinched by the chamber and created an over pressure. I have seen it happen, and it isn't pretty.
This is what caused me to get a chamber gauge. All the Wylde chambers I've measured so far have come out 1.790. I measure the chamber before I put a round through it.
 
Thanks to everyone who replied, or will reply in the future. Rather than me replying to each individually let me try to answer all in this post. I hope I don’t miss anyone.

It was not raining. Perfect weather, 70 degrees, partly cloudy.

I do have quite a bit of Varget :) however I’m starting to use X-Terminator in place of it for many loads. I’m getting good results with X-Terminator and it’s cheaper.

I have inspected with a bore scope. I don’t have a carbon ring.

I will stick that case in the chamber, come in from the muzzle with the bore scope and see if I can look at the case mouth and the neck of the chamber to try to determine if there’s a length issue there, if that makes sense.

This brass, I bought 200 LC brass from an on-line vendor who has been around for quite a while. I had ASSUMED I was buying once fired LC 5.56 because, well, that’s a common thing but looking back, in fairness, it was not advertised as “once fired.” Just “hand sorted.” My mistake. All of the cases had fired primers but many of them had the crimp previously removed so who really knows how many firings they had endured. The one that is the subject here is LC96 (!) Been around a few years I guess. I never really looked at the date before this. Again, I ASSUMED.

One conclusion I’ve come to is, I’m only buying new brass going forward. Fired brass is false economy.

I used to shoot at a DNR public range. Lots of 223/5.56 brass left on the ground by others. They used to have a guy come in and remove all the brass frequently on the understanding that he was scrapping it. They found out he was selling it as “once-fired” for reloading. They don’t let him take it any more.
 
i've been shooting 53 vmax at 3500-3600 (prob 55-60kpsi easy) out of my 223 for almost a decade now. the lapua brass i'm using currently has at least 10 firings on them, never an issue of any kind.

my n133 load is compressed, and i probably couldn't get enough of it in the case even if i tried really hard, to have any sort of catastrophic event occur. n133 is considerably faster than varget, so idk how you could come near the pressures to necessary to cause any sort of case failure.....i dont care how bad a carbon ring, or whatever else is.

all signs lead to a bad piece of brass IMO
What is your N133 load to get near 3600 on the rounds, if you don’t mind me asking. I’m using 24.2 of the N133 with 52 SMK’s and getting like 3200 on most rounds. Lapua brass.
 
What is your N133 load to get near 3600 on the rounds, if you don’t mind me asking. I’m using 24.2 of the N133 with 52 SMK’s and getting like 3200 on most rounds. Lapua brass.
26.1 grains with my 21 lot gave me 3,600 with bullet jammed
26.1 grains on my new 23 lot is 3,570 also jammed

don't be afraid to step it up, i wouldn't work up more than 0.2 grains at a time, but i found the most consistency in mv es/sd near max and the bullets jammed. shot a 5 shot 0.8" group today at 200 yards with my factory rem 700

IMG_1704.jpeg
 
Thanks to everyone who replied, or will reply in the future. Rather than me replying to each individually let me try to answer all in this post. I hope I don’t miss anyone.

It was not raining. Perfect weather, 70 degrees, partly cloudy.

I do have quite a bit of Varget :) however I’m starting to use X-Terminator in place of it for many loads. I’m getting good results with X-Terminator and it’s cheaper.

I have inspected with a bore scope. I don’t have a carbon ring.

I will stick that case in the chamber, come in from the muzzle with the bore scope and see if I can look at the case mouth and the neck of the chamber to try to determine if there’s a length issue there, if that makes sense.

This brass, I bought 200 LC brass from an on-line vendor who has been around for quite a while. I had ASSUMED I was buying once fired LC 5.56 because, well, that’s a common thing but looking back, in fairness, it was not advertised as “once fired.” Just “hand sorted.” My mistake. All of the cases had fired primers but many of them had the crimp previously removed so who really knows how many firings they had endured. The one that is the subject here is LC96 (!) Been around a few years I guess. I never really looked at the date before this. Again, I ASSUMED.

One conclusion I’ve come to is, I’m only buying new brass going forward. Fired brass is false economy.

I used to shoot at a DNR public range. Lots of 223/5.56 brass left on the ground by others. They used to have a guy come in and remove all the brass frequently on the understanding that he was scrapping it. They found out he was selling it as “once-fired” for reloading. They don’t let him take it any more.
Once fired LC brass would still have a primer crimp.
If I were you, I'd ditch that brass and buy something new to eliminate as many variations as possible.

Consider it a learning experience. We've all had them, unless you're due for one.

I do use LC brass for my AR where the brass may likely be lost. They're rather anemic loads and sooner or later I'll probably wish I hadn't done that. But if it doesn't have a crimped primer when I buy it, it goes in the scrap bucket.
 
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