# Neck Tension and Velocity



## Savage260 (Oct 21, 2007)

I have read lot about neck tension and if it is that important or not. I recently was loading my .338 Edge for deer season. As I was seating the 300gr SMKs into the REM brass I took note of which seated easily and which needed more force to seat. The harder seating were placed on the left side and the easier on the right side of my ammo box. When I took the chrono out I fired 5 from each side picked randomly. The side that took more force to seat, which I take to mean they have more neck tension, were between 2794 and 2798fps with an average of 2795.8fps. I was very happy with these results, and these 5 were also very accurate. The 5 I shot from the easier seating side were not even close to as accurate, and shot from 2746 to 2782 fps. Is this all due just to the neck tension, or might there be other factors at play? All loads were thrown and measured the same way and all brass was prepped to be as close to the exact same as I can get them. I didn't have time to run them on the consentricity gauge, so that might play a part. What do you all think about these results. Mostly due to neck tension or other factors?


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## AdamFisk (Jan 30, 2005)

I don't like your results. Means I have to get a little more anal in my reloading. How was the brass prepped? FL sized?

As Deano would say, consistency is accuracy. I'm starting to believe one needs to pay more attention to neck tension.


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## Plainsman (Jul 30, 2003)

What your talking about is how Lee advertises it's factory crimp die. When I was trying to get a very accurate load in my DPMS in 223 I just could not match the Blackhills load. Not until I crimped it with a Lee factory crimp die. I crimped them until they slightly deformed the bullet. That's a lot.
I tried the same thing in my 308 with no results. I tried it in the 22-250 which gave me less accuracy. However, the bottom line is more neck pressure pushes up pressure. Sometimes with large capacity more pressure means more consistent powder burn. Every chamber, and every barrel is different. If you don't mind spending a couple of bucks call the manufacturer of you dies and buy another sizing die spindle. Then mic your brass and those with the thinner neck size with the spindle that you have reduced the expander ball. 
Simply put your spindle in a drill and turn down the expander ball with 1000 grit emery cloth. Don't do it if you have only one expander ball. 
That is the old cheap way I did it in the past. Now I neck turn for consistency. It is under $50 to get set up, and only about $10 for each caliber after that. That is if you have a compatible case trimmer. My setup is RCBS. I didn't buy the power model and just the old crank gives me consistent neck tension on my 6.5 X 284 in -------maybe 15 seconds.

The only way to increase neck tension though, is by the old simple drill and emery cloth. You don't need a tighter neck in your sizing die, a smaller expander ball will do the trick.


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## People (Jan 17, 2005)

Here is a URL that will give you lots to think about.

http://bulletin.accurateshooter.com/201 ... -consider/

I load many rds at a time. I try to get at least one full year or two full years of ammo loaded at a time. Here is what I do. I always use HBN on my bullets. It used to be Molly. Once I find a load I will load up 20 extra and hold onto them for at least 6 months. Then I will fire some of them. If accuracy has held I will load up the rest and shoot as normal.

The reason I started doing that was I loaded a thousand .308W rds many years ago and over the years they are starting to show higher and higher pressures. When I loaded them I know the casings had sat for well over a month since being resized. These bullets where bare and they were less speed than M80. I have not tested the speed recently as I do not know how fast they were shooting before. I tried to pull one and it was much harder to pull than one would think. I pulled the bullet of a few recent reloads and they pulled much easier.

After taking a steroids test doctors informed Chuck Norris that he had tested positive. He laughed upon receiving this information, and said "of course my urine tested positive, what do you think they make steroids from?"


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## Savage260 (Oct 21, 2007)

Adam, the brass was all once fired, primers were taken out before tumbling, then vibed in corn cob media. I neck sized them then trimmed them all to within +-.001 using my caliper. I chamfered and deburred the case mouth. That is about it. I have yet to get the time to try annealing, or try weighing cases. Pretty simple stuff. I think I may have been experiencing some of what was talked about in the URL people posted. I am guessing the left over carbon in some of the cases acted as a lube where the cleaner cases were more "grippy". Either way, I am going to use my ultrasonic cleaner next time and see what happens when they are all super clean.

Plainsman, I set all my dies to have absolutly no crimp when seating, am I correct in assuming you thought I might be crimping my cases around the bullets?


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## xdeano (Jan 14, 2005)

The only way to get consistent neck tension is to us an expander mandrel, push the necks out, turn the outside and resize. This pushes all the imperfections from the inside to the outside to be cut off. Resize with either a button of the correct size again or with a bushing die to give you concentric necks with consistent neck tension. I like around 2 thousandths tension. This give enough grip so you can't push the bullet into the case if you push it against the end of a table, but doesn't fall out if you jam them into the lands and extract.

another way to get better neck tension is to honing out the inside of the neck, similar to honing the piston walls of an engine, just give for better contact. Don't do to much, just enough to rough it up. 1000grit will do this just fine.

Or better yet just get a different expander button on your die, they're cheap and you can get the size you want.

I tend to use sizing bushings instead of sizing buttons because the sizing buttons tend to stretch the necks a hair when the necks are being removed from the die.

This is a good discussion.

xdeano

edit: I do think that neck tension and velocity have a direct correlation.


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## Plainsman (Jul 30, 2003)

> Plainsman, I set all my dies to have absolutly no crimp when seating, am I correct in assuming you thought I might be crimping my cases around the bullets?


No. I knew you were not doing that, but I think neck tension may be what is giving you the difference. I was saying neck tension is one of the reasons Lee touts their crimp dies. The Lee crimp die helped my accuracy a lot in the 223 out of my AR15. Not my other calibers.



> edit: I do think that neck tension and velocity have a direct correlation.


No doubt about it. Crimping with a Lee crimp die pushed velocity in a 16 inch barreled 223 (26 gr H335 and 50 gr VMax) up about 35 fps.


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## Csquared (Sep 5, 2006)

How far off the lands are your bullets?


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## Savage260 (Oct 21, 2007)

The rounds I loaded for hunting are way, way off the lands. The magazine really limits my OAL with this Edge.


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## Csquared (Sep 5, 2006)

Makes sense. Forget the magazine. Most of mine are single shots anyway. You'll never need a second shot :wink:


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## Savage260 (Oct 21, 2007)

I spent an extra $85 for the magazine(before I found out the mag would limit me that badly) when I ordered the XLR Industries stock. I have to use it at least a little. The idea was to shoot my deer at or beyond 400yds, so I thought an extra round or two would be a good idea. I plan to do most of my shooting with this rifle in the single shot configuration. Ended up cleaning a big bodied 3x3 out of the gene pool at only 253yds. So much for the best laid plans.....


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