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New brass - full resize or neck only? |
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sakomato
Optics Master Joined: February/28/2008 Location: Houston Status: Offline Points: 1166 |
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Hey Sgt D, the fired case will not be out of round or have runout (chambers are almost always concentric or close to it). When you fire the case the brass will iron itself to the chamber walls and will be very concentric on the outside. Any variances in neck thickness will migrate to the inside of the neck. Where it becomes out of round with runout is when you start resizing it.
Like Dave Wilson said, the expander ball is usually the culprit and it will jerk the shoulder and neck around. If you size with the expander then that will size the inside of the neck brass and push variances in neck thickness back to the outside of the neck which will show up as runout but is really not. If you size without the expander in a FL die then you would need to neck turn so as not to get too heavy a bullet grip but that would reduce runout since most dies are also very concentric.
If you use a Lee Collet then you will have less runout because the Lee Collet has a floating mandrel which will center before the collet is squeezed onto the neck.
With a bushing type neck sizer most of us remove the expander ball because you might as well be using a FL die if you use a bushing die with an expander. Without the expander you can buy a bushing to fit the size you want on the outside of the neck. But again, you need to turn to get the best results because the bushing will size the outside of the neck and push all the neck thickness variations to the inside, that will lead to good runout on the case neck before seating the bullet, but bad runout after seating the bullet since the bullet will push the inconsistencies back to the outside and push the bullet one way or the other.
Lot to think about. Best course is to use a Lee Collet Neck Sizer and Redding Body Die and you have solved 95% of runout problems without a lot of hassle. Edited by sakomato - February/24/2009 at 20:16 |
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Guns only have 2 enemies, rust and politicians
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supertool73
Optics God Superstool Joined: January/03/2008 Status: Offline Points: 11814 |
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Hope I can explain what I saw on the vid with this. David tubbs said that based on the brass that the entire case can in fact become unstraight in a chamber upon firing and will stay that way. He said what causes this is if the case walls are not even from side to side or at lease very close that the thinner side will stretch and it will bend like a banana. (obciously not that much but that was just the example that he used) He said it is more likely in a action like a Rem 700 because there are only the two locking lugs for it to push against when firing. If you put the thin side so it is not pushing on the lug but so it is in position in front of nothing that the brass will actually stretch that way. That is one reason why a lot of bench rest shooters put their brass in the exact same way every time, so they can line up the weak and strong side perfectly with the lugs on the bolt. He use a guage to measure the case walls of his brass and throws out anything that was over .003 variance from side to side. He said using an action with more than two locking lugs definitely helps this problem. But for extreme accuracy and consistancy we just need to be checking the case all thickness often and throw out the brass that is much out of spec. Obviously this is for the most extreme accuracy obtainable and will not apply to most of us, just thought it was some very interesting info. |
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cheaptrick
MODERATOR Joined: September/27/2004 Location: South Carolina Status: Offline Points: 20844 |
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What Roy said.
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Sgt. D
Optics Master Extraordinaire Joined: February/20/2008 Location: North Carolina Status: Offline Points: 4525 |
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So when I am sizing the neck on new brass or pushing primers and sizing fired brass the resistance I am getting on the return stroke is "possibly" causing runout. Or maybe even pulling the neck and shoulder out of place. This is getting frustrating. I had wondered why the pull stroke was smooth and had almost no resistance, but the return is usually tight at the end. Is there an adjustment to reduce this or do I need different dies? I am using RCBS now.
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Take care of Soldiers, Show em how its done and do it with em, Run to the Fight & and hold your ground! I die my men go home! If you're a NCO and this ain't you. GET OUT! GOD BLESS AMERICA!
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supertool73
Optics God Superstool Joined: January/03/2008 Status: Offline Points: 11814 |
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David Tubb recommends taking the expander ball that goes inside the case and sanding it down a little smaller. That is what he did in the video. He says they are to big to start with and will pull to much and cause run out. He chucked the whole expander ball assembly in a drill and used sand paper and emery cloth to make it smaller.
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Lifetime warranty and excellent customer service don't mean a thing when your gun fails during a zombie attack.
"A Liberal is a person who will give away everything they don't own." |
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cheaptrick
MODERATOR Joined: September/27/2004 Location: South Carolina Status: Offline Points: 20844 |
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Or, you could throw the factory expander ball in the trash like I did and use a K&M Case Neck Expander, if and when necessary.
I believe that the expander button, along with the case trimmer pilots, are the 2 biggest culprits causing run out.
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Steelbenz
Optics Jedi Knight ROLL TIDE ROLL Joined: January/03/2006 Location: Heart of Dixie Status: Offline Points: 5153 |
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+1 |
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"Don't argue with a fool! From a distance you can't really tell who's who!"
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Sgt. D
Optics Master Extraordinaire Joined: February/20/2008 Location: North Carolina Status: Offline Points: 4525 |
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Ok if I trash the expander ball, what will determine the need for a expander? Do I have to mic each case or is it easy to see? I don't mind an extra step of two as long as it doesn't cause problems somewhere else.
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Take care of Soldiers, Show em how its done and do it with em, Run to the Fight & and hold your ground! I die my men go home! If you're a NCO and this ain't you. GET OUT! GOD BLESS AMERICA!
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sakomato
Optics Master Joined: February/28/2008 Location: Houston Status: Offline Points: 1166 |
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Hey cheaptrick
What size does the K & M expander size the inside of the neck to? How much bullet grip does it give?
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Guns only have 2 enemies, rust and politicians
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300S&W
Optics God Joined: January/27/2008 Location: Burlington,WV Status: Offline Points: 10592 |
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I use a universal depriming die and Lyman "M" dies instead of the expander/depriming rod assembly.
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cheaptrick
MODERATOR Joined: September/27/2004 Location: South Carolina Status: Offline Points: 20844 |
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I have one for a .308, so it expands the case mouth to .308.
Neck tension obviously is very minute on most quality bullets.
If that's the case I just run them through my Lee Collet die to get a few thousands neck tension .
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sakomato
Optics Master Joined: February/28/2008 Location: Houston Status: Offline Points: 1166 |
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So you would have to have another die to size the neck after the K & M expander. If you have the Lee Collet then why do you need the K & M expander?
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Guns only have 2 enemies, rust and politicians
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cheaptrick
MODERATOR Joined: September/27/2004 Location: South Carolina Status: Offline Points: 20844 |
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I only use the K&M expander to open the case mouth on virgin brass to turn necks or just open the case mouth if it gets pinched.
The K&M expander only sizes the inside of the brass, not the outside.
I have used the K&M tool on several occasions to expand the necks and the bullet seated OK, with little bullet "grip". But some rounds are too loose and will slide up and down.
So to get consistent neck tension, I run all the brass again through my Lee Collet die.
Actually, once the brass is fired, you will only have to size the outside of the brass any how, thus eliminating the need for the dies expander button.
I apologize for not explaining myself better.
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BillyWayne
Optics Journeyman Joined: February/27/2009 Location: New Hampster Status: Offline Points: 408 |
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I cannot get new brass into my Lee Collet dies. The necks are to tight. But once they have been blown out the Lee Collet works great.
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John 11:35
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Big Stick
Optics GrassHopper Joined: March/08/2009 Status: Offline Points: 4 |
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Never move brass,without a reason.
Neck sizing virgin hulls will round necks,align neck tension and preclude inducing headspace woe. Easy to back an FL die off,to accomplish sizing the greatest portion of the neck,less influx of setting a shoulder back.
Die/chamber geometry is the most misunderstood and most botched facet of Reloading.................
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