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Discussion Starter · #1 ·
I now understand why the military wants to crimp their bullets but since they shoot the 5.56, why is there crimped .223's? Does the gov. buy and use .223's

Also... I have trimmed a little too much off of 150 cases of .223's. They got down to 1.739 to 1.745. "Trim to length" says 1.750. Have I goobered up these cases? And how far is too far on the length?

I'm amazed at how much smarter I get every day.

Mike
 

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Let me see if I can help a little, and cover crimps at both ends of the cartridge. Starting with the primer pocket crimps. This is something that was/is done for guns that fire from an open bolt. If you're not familiar with the term, it is most generally applied to full automatic, or some select fire arms. This is when the gun is not being fired, the bolt is stopped in its most rearward position. Pulling the trigger releases the bolt to come forward, pick up a cartridge from the magazine, chamber it and fire. It will do this as fast as the cyclic rate of the weapon allows, until the trigger is released. The primer pockets were/are crimped to prevent the primer from backing out and causing a premature firing before the cartridge is fully chambered. The bullets are crimped to keep them from being pushed back into the case during the chambering process when the bolt is travelling forward. The bullet being pushed back into the case could cause a dramatic increase in pressure when firing. It could also push the bullet completely back into the case spilling the powder into the action, and rendering that cartridge useless, plus the chance of tying up the action of the weapon. Another reason for the bullet crimp is if the cartridge is loaded with ball powders, you will get more consistant ignition cartridge to cartridge with a uniform crimp. The cartridge length you have listed is kind of short for some of them, especially if you are shooting them in guns that need to have the cartridges crimped. Your cases need to be within about .002 and no more than .004" difference in length to get consistant crimps It isn't a problem if they are all short, or all at or close to SAAMI specs. If your shooting them in a bolt gun or a single shot, this .011" probably wont make much of any difference in your accuracy. Hope some of this will help.
 

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Discussion Starter · #3 ·
Wow. Perhaps I should toss the short cases.

Great explanation, thanks.

Does the military buy/shoot .223's?
 

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Wow. Perhaps I should toss the short cases.

Great explanation, thanks.

Does the military buy/shoot .223's?
I don't think its just the military. As an example some rifles are chambered strictly for the 5.56 military cartridge. Some are compatable with either the 5.56 or the .223 Remington. The cartridge dimensions are the same, the the 5.56 is loaded to a higher pressure than the .223 Rem., it also has different dimensions/specs for the throat/lead of the rifling. SAAMI says that rifles chambered for the .223 Remington are not safe for firing 5.56 military ammo for these reasons. The rifles that are compatable with either cartridge have throats cut to keep the pressures down to a safe level when firing military style ammo. Rifles with the chamber cut for 5.56 military are supposed to be safe with all .223 Rem. ammo. As for the cases, I wouldn't toss them. If you have a goodly ammount of them, just trim all of this bunch to the same length and use them as any other. Don't mix them with cases trimmed to the proper length. Load them like any other case, .011" short isn't going to create any problems. You just cant crimp them with cartridges trimmed to the proper length.
 

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like twicepop says dont dump them just trim that whole batch to that same length, and keep them separate, ive made that mistake a few times myself, i have a little custom made 223 with a mauser action thats what i shoot them in, and they are still very accurate,
 

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I would load some of the brass you trimmed and check the headspace first
 

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No need to chuck those cases if that's all the shorter they were trimmed. As mentioned, you might want to trim the rest of that batch to the same length to get a uniform crimp...if you're crimping these loads. If not crimping, don't worry about it at all.



I would load some of the brass you trimmed and check the headspace first
Don't have to worry about that extra (erm...missing) 0.01" causing headspace issues on a bottleneck rifle cartridge. On a straight-wall case yes, but not a on a bottleneck. The headspace on those types of cartridges are determined by the datum line on the shoulder, not the case mouth.
 

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You will find crimped ammo in a lot of different cartridges and manufactures. Military 5.56, 308 and 30-06 will always be crimped for the reasons stated above.

You will also find factory crimped ammo in rounds like the 30-30, this ammo is crimped because most rifles chambered in the 30-30 are tube feed magazines and crimping helps keep the bullet in place.

Some manufactures crimp their ammo for reasons only they can tell you. I have seen factory crimped ammo in a variety of cartridges non of which have anything to do with Military, cartridges like the 7mm-08 and 338 Win Mag.

Why is some of your 223 ammo crimped? Same reason the 5.56 ammo is crimped. 223 Rem ammo can be safely fired in a 5.56 chamber as the external dimensions are the same. Knowing this ammo manufactures have to assume their 223 ammo could be fired in a 5.56 semi-auto or even full auto rifle. Securing the bullet with a crimp ensures that their ammo will function in both.

Here is what Sierra has to say about crimping for Semi-Autos:

Neck Tension

When we stop to consider the vigorous (read, downright violent) chambering cycle a loaded round endures in a Service Rifle, it becomes pretty clear it suffers abuse that would never happen in a bolt-action. This is simply the nature of the beast. It needs to be dealt with since there is no way around it.

There are two distinctly different forces that need to be considered: those that force the bullet deeper into the case, and those that pull it out of the case. When the round is stripped from the magazine and launched up the feed ramp, any resistance encountered by the bullet risks having it set back deeper into the case. Due to the abrupt stop the cartridge makes when the shoulder slams to a halt against the chamber, inertia dictates that the bullet will continue to move forward. This is exactly the same principle a kinetic bullet puller operates on, and it works within a chamber as well. Some years ago, we decided to examine this phenomenon more closely. During tests here at Sierra’s range, we chambered a variety of factory Match ammunition in an AR-15 rifle. This ammunition was from one of the most popular brands in use today, loaded with Sierra’s 69 grain MatchKing bullet. To conduct the test, we chambered individual rounds by inserting them into the magazines and manually releasing the bolt. We then repeated the tests by loading two rounds into the magazine, chambering and firing the first, and then extracting and measuring the second round. This eliminated any potential variation caused by the difference between a bolt that had been released from an open position (first round in the magazine) and those subsequent rounds that were chambered by the normal semi-automatic operation of the rifle. Measuring the rounds before chambering and then re-measuring after they were carefully extracted resulted in an average increase of three thousandths (0.003") of forward bullet movement. Some individual rounds showed up to seven thousandths (0.007") movement. Please bear in mind that these results were with factory ammunition, normally having a higher bullet pull than handloaded ammunition.

To counteract this tendency, the semi-auto shooter is left with basically two options: applying a crimp or increasing neck tension.



As for Me. I crimp all my ammo for Semi-Autos with the Lee Factory Crimp die. It helps secure the bullet, improves accuracy and case (trim-to-length) is not critical.


As for your short brass, do not toss them, especially in these troubled times. Load em and shoot em, they will grow with each FL sizing. If you are going to crimp, get a Lee Factory Crimp Die, you can thank me later.

OH, BTW there is a "sticky" at the top that shows the difference between the 223 and 5.56, good read.
 

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Discussion Starter · #9 ·
Steve4102,

You stated that "case (trim-to-length) is not critical". Hence my dilemma with the short trims. I'm not familiar with the Lee Factory Crimp Die but I will be as soon as I buy one. My question: How does the crimper know where to crimp if the case lengths are slightly different?

On another note, I've been doing my trimming with my new "Little Crow Trimmer" Some come out long, some shorter depending on how much pressure I hold and it shouldn't be doing that. I've called the company and can't get anyone just yet. Here's a link the their page:
http://www.littlecrowgunworks.com/wft.html
Anyway that's why the difference in the length. I'll try the Lee Trimmer.
 

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Discussion Starter · #10 ·
Steve4102,

Duh... I have a Lee crimping die. It's one of the dies I haven't gotten to yet. I'd ordered a Hornady 233 die set from Cabellas along with several other items (Christmas Present from the wife). As the items began to arrive and I got notices to pick tem up so I called the store in Allen TX and ask that they hold all items till everything came in. I live 250 miles away from the store and they held everything except my Hornady dies and the shell plate for the 223. They were sold to someone else. They were very sorry and tried to make up by giving me the Lee set.

I'm still discovering.

Thanks so much for all the info!
 
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