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Old October 5, 2012, 06:10 PM   #1
rebs
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seating depth and OAL ?

I wanted to ask you guys that reload 223's what OAL do you seat to ?
I have found a real accurate powder and bullet combo, actually a few bullets that are extremely accurate. Now I want to play with bullet seating depth and see what effect it has on accuracy.
I have all 55 grian bullets, hornady flat base soft points, hornady 55 grain fmjbt's, dogtown 55 grain flat base soft points and some hornady vmax. They are not all the same length so if I load them all to the same OAL some are at the canalure and some are not and vice versa if I load to the canalue they are not all the same OAL.
What are you guys doing about OAL with bullet ?
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Old October 5, 2012, 08:22 PM   #2
Brian Pfleuger
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The cannelure doesn't matter unless you're crimping. Seat them where they're most accurate.
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Old October 5, 2012, 10:25 PM   #3
steve4102
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Bolt action or AR?
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Old October 6, 2012, 07:21 AM   #4
rebs
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this is for an AR
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Old October 6, 2012, 08:24 AM   #5
steve4102
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I seat to just under mag length of 2.255 +/-. I don't play around much with OAL in my 223/5.56 AR. Mag length ammo already has a substantial jump in my 5.56 chamber and seating deeper has not shown me much if any improvement. YMMV. Crimping with the Lee Factory Crimp die has shown improved accuracy in my AR so I use it on all my Semi-Auto ammo.
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Old October 6, 2012, 10:07 AM   #6
tobnpr
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I agree. They're light bullets and there's not much reason to play with seating depth, as you're gonna have a long jump no matter what...
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Old October 6, 2012, 02:37 PM   #7
rebs
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So you guys suggest just se4ating to the canalure ?
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Old October 7, 2012, 12:30 AM   #8
DeerSlayer86
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In an AR just seat to the mag length...unless you're shooting a lead free bullet like the Hornady GMX, Nosler ETip, or barnes. As far as the cannelure, it's an AR, so you are crimping, but you don't have to crimp at that point...just ignore it
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Old October 7, 2012, 07:18 AM   #9
rebs
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I have not been crimping. I have loaded over 1000 rounds and not crimped any of them for my AR.
Could someone explain why I should be crimping ?
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Old October 7, 2012, 07:27 AM   #10
steve4102
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Quote:
Could someone explain why I should be crimping ?
This is why I crimp with the Lee Factory Crimp die, Plus the LFCD improves accuracy in all my Semi-auto handloads.


From Sierra

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.



Link
http://www.exteriorballistics.com/re...sgunreload.cfm
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