.223 case crimping


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Kevwyo
March 30, 2010, 01:18 AM
Tried the THR search feature but for some reason unknown to me I keep getting a totally blank page.

All I would like to know is if crimping .223 cases is necessary.

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Grumulkin
March 30, 2010, 01:24 AM
No, it's not necessary even in a semiauto.

steve4102
March 30, 2010, 04:07 AM
Yes, In a semi-auto.
Here is what the experts at Sierra have to say.



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.

nicholst55
March 30, 2010, 06:46 AM
Thanks for posting that, Steve. This is something that has long been speculated, and something that I had intended to test for my own satisfaction once I return to the States. I think you saved me the trouble! ;)

Guess it's time to buy some taper crimp dies.

shootinxd
March 30, 2010, 06:54 AM
Lee FCD,you can set is light or hard crimp as you like.

Fatelvis
March 30, 2010, 07:09 AM
Thats another reason to not load to max for your match rifle. I don't crimp my competition loads, although I kind of like the idea of the bullet "automatically" seating itself to touch the rifling! :D

JimKirk
March 30, 2010, 07:33 AM
I could see where that would be a problem with a match type chamber, but most "service" chambers are rather loose compared to match type, especially in the throat area.

If a bullet moved forward in a long throated 5.56 chamber, it probably would help accuracy by getting the bullet closer to the rifling.

Now if it slammed forward enough to jam into the rifling, then I could see pressure problems.

I think a better solution would be to size your expander ball where there would be sufficient neck tension to hold the bullet at least as tight as factory loads.

But I tend to think along accuracy lines more than bang bang shoot'um up lines....
I rather have the consistency of not crimping verses the inconsistency that crimping adds to the picture.

Jimmy K

steve4102
March 30, 2010, 08:35 AM
I crimp all my semi-auto loads with the Lee Factory Crimp Die. I crimp both cannelured and non-cannelured bullets. I have found the LFCD to increase accuracy not degrade it.

I have tested the affects of increased neck tension in my 300WSM BAR and Ruger Mini-30. Long story short, the more neck tension the worse the accuracy.

Targets at 100 yards using the LFCD.

AR-15, 223 five rounds.
http://i2.photobucket.com/albums/y17/steve4102/223V-Max.jpg

AR-15 6.5 Grendel.
http://i2.photobucket.com/albums/y17/steve4102/Grendel25202.jpg

Browning BAR 300WSM.
http://i2.photobucket.com/albums/y17/steve4102/300WSMMitch.jpg

Ruger Mini-30.
http://i2.photobucket.com/albums/y17/steve4102/File0044.jpg

243winxb
March 30, 2010, 08:50 AM
To counteract this tendency, the semi-auto shooter is left with basically two options: applying a crimp or increasing neck tension. Military rounds have a bullet pull of 35 to 45lbs. Without a crimp, i can get 45lbs using RCBS dies. To roll crimp, make sure your brass is trimmed to exactly the same length or you will end up bulging the neck or shoulder area. Then the round will not chamber and will get stuck in the chamber when trying to extract it. Taper crimp is much more forgiving with different case lengths, but useless IMO. Lee seating dies taper than roll.

HOWARD J
March 30, 2010, 09:50 AM
@steve4102

When you crimp with a Lee Factory Crimp die --do you ever get a cannelure on your cartridge case ??

JimKirk
March 30, 2010, 10:05 AM
Steve
What I'd like to see...is side by side targets of crimped verses non crimped.

I have not tested it myself in semi-auto rifles, but I have done intensive testing with bolt action guns. My results were completely opposite of what you have found. Non crimped ammo was more accurate than crimped.

If this "crimped ammo" is more accurate then why are the benchrest shooters not crimping their ammo?

Jimmy K

Grumulkin
March 30, 2010, 10:12 AM
Semiauto rifles I've loaded for include a Remington 742 in 308 Win., an M1A in 308, Garands in 30/06, a couple of 223s, a 7.62X39 and a 458 SOCOM. The ONLY malfunction I had was years ago when I tried to crimp for the Remington 742. Since then, and after thousands of rounds, I've never crimped for any semiauto rifle.

I have compared accuracy of crimped vs uncrimped bullets in various cartridges. The only instance in which I found a definite increase in accuracy was in 45 Colt loads. Most of the time it doesn't make any difference.

rcmodel
March 30, 2010, 01:02 PM
I don't crimp for AR-15's, or at least hardly ever.
It is not necessary if you have proper neck tension.
And rifles & magazines that feed right.

Crimped & not crimped in CZ-527.
http://i81.photobucket.com/albums/j219/rcmodel/KTOG/Crimped1.jpg

http://i81.photobucket.com/albums/j219/rcmodel/KTOG/Crimped2.jpg

rc

steve4102
March 30, 2010, 06:02 PM
I have not tested it myself in semi-auto rifles, but I have done intensive testing with bolt action guns. My results were completely opposite of what you have found. Non crimped ammo was more accurate than crimped.

In your testing what type of crimp did you use. I never had good luck with the crimp feature on my seating dies or a taper crimp die. The LFCD is a different animal as far as I am concerned. It works great, holds the bullet secure and increases accuracy.

If this "crimped ammo" is more accurate then why are the benchrest shooters not crimping their ammo?

I know that Benchrest shooters do not crimp. I also know that many Benchrest techniques are not the best thing for hunting rifles and sporting rifles. Things like loading long and pig jamming the bullet into the lands, things like loading single shot, things like indexing the loads so as to chamber each round the same way each time, etc.etc. These things and many more are all well and good for the Benchrest shooter, but they are not always the best thing for the average Hunter and shooter.

By saying, if the benchrest crowd doesn't do it,then it must not be good for anyone is the same as saying, if the benchrest crown does it it must be good for everyone. This just ain't so. Different techniques for different situations.


I have done extensive testing with neck tension vs LFCD. Using my Redding bushing dies I have tested bullet creep with various amounts neck tension. Starting at .001 and increasing neck tension to .006, I found that the bullet creep in my Browning and Ruger remained unchanged. Cycling the action and measuring OAL showed little or no change in the amount of bullet creep no matter the neck tension. Accuracy was consistant up to and including .003 neck tension, after that accuracy gradually went to hell. .006 was plan old HS.

Starting with .002 neck tension and applying a medium light LFC held the bullet in place much better. There was still a slight amount of bullet creep, but not near as much as without the crimp. Accuracy was unchanged in the Browning and better in the Ruger when applying the crimp. So, I choose to crimp, I know my bullet will be seated right were I want it during the violent cycling of the action and I know my accuracy is on target.

I have not tested my AR-15 for bullet creep with various amount of neck tension as I do not have bushing dies for the 223. All I have tested in the amount of creep with the LFCD vs without. I must say that the amount of creep is substantial less than in my Browning and Ruger Mini-30. Maybe due to the action maybe due to the lighter bullet. Either way, I choose to crimp and my accuracy has not suffered. YMMV.

243winxb
March 30, 2010, 06:22 PM
I am sure its a fine tool, if used correctly, but if its not, your case mouth and bullets might look like this > http://i338.photobucket.com/albums/n420/joe1944usa/LeeFCD-1.jpg http://i338.photobucket.com/albums/n420/joe1944usa/LeeFCD.jpg :(

JimKirk
March 30, 2010, 06:33 PM
Steve you win ...

I'm not getting into the LFCD argument with you..... have at it..

Jimmy K

steve4102
March 30, 2010, 07:13 PM
Sorry Jim, didn't mean to offend anyone here, just reporting my experiences with the LFCD. As I ended my last post, YMMV.

EddieNFL
March 30, 2010, 07:20 PM
I think a better solution would be to size your expander ball where there would be sufficient neck tension to hold the bullet at least as tight as factory loads.

Agreed, or use bushing dies.

I've pulled more than a few bullets after chambering in ARs. Neck tension of 0.002" works well. A crimp alone will not prevent setback, but proper neck tension can.

steve4102
March 30, 2010, 07:26 PM
A crimp alone will not prevent setback, but proper neck tension can.



I all my testing with the LFCD and varying degrees of neck tension I have never once had "setback". In all my tests the bullet creeps forward, never backwards, so I cannot comment on weather neck tension or crimping works best. I do know that neck tension above .003 was detrimental to accuracy in my rifles, YMMV.

JimKirk
March 30, 2010, 10:58 PM
Not offended Steve ... took me a while, but I learned when to say when.

Good luck

Jimmy K

Floppy_D
March 30, 2010, 11:27 PM
This is exactly the same principle a kinetic bullet puller operates on, and it works within a chamber as well.

True, but have you ever tried to use a kinetic bullet puller on a 223 round? It's a workout!

I don't crimp for AR-15's, or at least hardly ever.
It is not necessary if you have proper neck tension.

My experience, though youthful compared to rcmodel's, is the same. I tried to pull some 55g bullets a while back, and broke the damned hammer in trying. It was a vote of confidence for the neck tension. Next good range day I get, I'll see if I can't make up a couple batches, and chamber half of them ten times to see if anything changes, with no crimping invloved. I am by no means a benchrest shooter, but I think that if the problem was manifested by one chambering, it should be visible by the tenth.

Happy shooting, all!

spleify
March 30, 2010, 11:45 PM
Very interesting. I have been hand loading for some time now but have just started loading .223. I think I will work up some various loads and make some tests of my own.

243winxb
March 31, 2010, 07:43 AM
I think I will work up some various loads and make some tests of my own. Now your talking. Doing your own test is the only way to know. But keep in mind brass changes with each loading. If the neck wall thickness happens to be at maximum, the working of the brass can have an effect. In 243win i have seen/measured the thinning of the neck case wall thickness. This is caused by the over sizing of the neck and the expander opening the neck back up using standard dies. When the neck thins to a certain thickness , thining stops. Bushing dies Rule

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