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Old January 17, 2010, 08:40 PM   #1
attila787
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cannelure bullets crimp?

Now that I bought my small base die set and have the perfect measurements. My last step is to crimp, BUT I really don't want too.

So do you guys think I need to crimp???? I'm reloading .223 bullets with the cannelured ring.
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Old January 17, 2010, 10:09 PM   #2
HiBC
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Some strongly advocate crimping .223 that will be used in a semi-auto.
The issue is a bullet setback in feeding.
If I do not have a cannelure,I do not crimp.If I had a cannelure,What the heck,I might do a light crimp.

This is assuming your brass is of a consistent length.

Then,I am not an authority,just IMO.
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Old January 17, 2010, 10:17 PM   #3
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I dont myself... but none of my guns for 223 are auto feed
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Old January 19, 2010, 12:44 AM   #4
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I use a light crimp.
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Old January 19, 2010, 04:56 PM   #5
Dirk00001
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I did a crapload of research on this, and based on my findings:

* Crimping degrades accuracy, regardless of whether or not the bullet has a crennalure.

* If there's no crennalure, you definitely do not want to crimp, regardless of whether or not the ammo is going in a semiauto.

* Assuming that your case is properly (neck-)sized, the amount of force required to push the bullet farther back into the case is greater than the force generated by the recoil of the rifle, as felt by those rounds bumping back and forth inside the magazine.

* Are you using bullets that are high enough quality that they are all the same length and have identical dimensions, is all of your brass extremely high quality (identical weights and powder volume) and sized and trimmed to an extremely high tolerance, and are your dies good enough to consistently seat the bullets exactly straight in the case? Because if you answer "no" to one or more of these - and I'm going to call BS if you don't - your bullets are already all loaded at different pressures. So unless you've loaded them to extreme pressure levels (in which case you better be sure that you answered "no" to the above questions, or at least are verifying each and every round you reload) losing a thousandth of an inch or two due to compression is quite unlikely to make any difference, safety-wise.

My suggestion: For semiauto use, work up loads to either max load data *or* until you just barely see signs of high pressure, then (if the latter) back off .2-.3 grains and use that as your load. And don't crimp anything, regardless of crennalures. I bet you'll get better accuracy than if you worked up a higher-pressure load with a crimp.
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Old January 19, 2010, 05:20 PM   #6
steelman762
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I was reloading that caliber last fall for my Mini-14. Some I crimped and others I did not. I did not see much differance in performance. You can get a factory crimp die from LEE where you don`t have to worry about the exact case lenght consistancy for roll crimping in a seating die. Yes if you crimp the bullet case too much and the crimp is not uniform you will loose accuracy as stated. I don`t think setback is a problem for us plinkers anyway
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Old January 22, 2010, 10:27 AM   #7
.284
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Not necessary. I agree with Dirk. There is not enough force to move that bullet deeper in the neck. I reload a 280 rem. bolt action and my neighbor reloads his 30-06 bolt action. We did before and after measurements with full magazines. We looked specifically at the 2nd and 5th rounds. Absolutely no change in length.

I do, as most reloaders do, roll crimp my 44 mag cases and yes my bullets have the cannelure groove. But, that's a magnum revolver and straight walled cases.....totally different.
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Old January 22, 2010, 04:17 PM   #8
Dirk00001
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I've read multiple articles about crimping being bad for accuracy and/or unnecessary; it's one of the reasons Sierra MatchKings (normally) don't have them. I've also read at least one article from a gun mag where the author went and tested the idea that crimping prevents the bullet from being pushed farther into the shell, which is where I got my data from - nothing he could do would cause the recoil against the bullet to reach the point where it would seat it deeper into the brass.

Aside from that, I've actually tested this out in one of my .223's with some high-end (uncrimped) loads; I put a primer-less, powder-less loaded round into my mag (figuring that without powder, and with an air hole into the case, the force required to push the bullet deeper would be decidedly less than if the round were loaded), and then would stack one or more rounds on top of that. I kept the same bullet at the bottom of the magazine for something like 50 shots, measuring with a caliper every 5 or so, and other than the *tip* being a little smushed it didn't move at all.

On the flipside, I wouldn't be at all surprised if one of the (unstated?) reasons for crimping is to allow for looser tolerances on the bullets and brass sizing; that way if your bullet is a little thin, and the brass was (re)sized a little large, it wouldn't make a difference. But if that's the case then I'm guessing you've still got more things to worry about than the bullet being pushed back one or two thousandths of an inch...
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Old January 22, 2010, 04:26 PM   #9
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I haven't been reloading rifles for as long as pistols. All my pistols are big-bore heavy revolvers so it was a given to do a good roll crimp. When I started reloading for rifles, I noticed some of the bullets had what appeared to be a cannelure on them. When I asked my experienced buddy about that he explained that it wasn't a real crimping cannelure. It was basically a marking that gave you a guide for seating depth. He advised against crimping for anything but tubular magazine lever actions. So I don't. I have loaded up some pretty heavy 7 MM Mags and 325 WSM ammo now. I looked at them really closely to see if there was any setback while in the magazine. None at all. I don't even think about crimping rifle cartridges now.
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Old January 22, 2010, 04:41 PM   #10
steve4102
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I load for 2 ARs, a Mini-30 and 2 Browning BARs. I use the Lee Factory Crimp die on all of these rifles. I have found the LFCD to increase accuracy and hold the bullet secure whether it has a cannelure or not. If you are going to crimp, get a Lee Factory Crimp Die. It works with all bullets and increases accuracy.

Here is what the Experts at Sierra have to say about crimping in a service rifle.

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.



AR-15, 52gr Nosler CC(no cannelure), crimped with the Lee Factory Crimp Die, 5 rounds 100 yards.




Ruger Mini-30, Crimped with the LFCD, 100 yards.


Browning BAR 300WSM, crimped with the LFCD, 100 yards.


No accuracy problems here by crimping non-cannelured bullets with the LFCD.
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Old January 22, 2010, 04:56 PM   #11
Dirk00001
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That's bizarre; I've tried the "chamber it test" as well (the test I did with the ~50 rounds would occasionally result in my test round getting chambered, as I was testing loads and so would only have a few rounds in the mag at a given time), and even that didn't move any of my bullets. ...but I reload my .223's solely in LC brass, and I can barely even get the bullets out with an inertial bullet puller, so perhaps (in my case, at least) it's the "increased neck tension" option...I just didn't know it.

But hey, as long as the bullet doesn't completely come out of the case, you're getting it closer to the lands than your magazine depth would normally allow, right? So just be sure to use really long bullets that like being as close to the lands as possible and you're good to go no matter what happens!

(...that's only partially a joke, actually; I use Berger 175 VLD's in my M1A, but I load them for magazine use so they're not as far out as they'd like to be...or at least, that's their state before chambering...)
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