Unexplainable high neck tension after annealing

H

Hunt

Sergeant
Full Member
Minuteman
Jul 3, 2005
651
72
Tennessee
#1
I'm a at loss of words to what I experienced yesterday while reloading. I was reloading some 175 SMKs in Lapua .308 brass yesterday when I experienced some unusually high neck tension. This was with Lapua brass that had been shot 6x and I had just annealed the brass using the Hornady annealing kit. One thing I noticed was that when I dropped the brass in normal tap water after annealing, I noticed it left some gray/dried lime looking scale in the primer pockets. I then cleaned them out as well as running a bronze brush back through the necks after drying. The neck tension was so high that it was leaving a pressure ring around the tip of the bullet to which I have never experienced this before while loading this setup. What am I missing here? My steps were as follow:

- tumble brass
- resize brass (using Forster press and F/L Forster sizing die). Nothing special here....Been using the same setup for 4 years.
- clean primer pockets
- clean lube from brass using alcohol and cloth
- anneal using 475 deg. Tempilac from Hornady kit and then dumping in tap water
- clean lime scale from primer pockets and brush necks using bronze brush
- seat primers
- charge with powder and seat bullet

What am I missing here?
 
#2
Re: Unexplainable high neck tension after annealing

Did you run them thru the sizing die again after annealing? I always do. My thought is that is expands as you heat it, then rapid cooling makes it contract. It could easily contract smaller than what you want. Thus giving the high amounts of neck tension, and or uneven neck tension through your lot freshly annealed brass.
 
#3
Re: Unexplainable high neck tension after annealing

First, skip the water quenching, let them air cool. Once the discoloration passes the shoulder and onto the case body, you’re done with that piece of brass. 6-10 seconds in the flame is all it should take.

Second, once annealed, the inside of the necks are super dry and clean. The coefficient of friction in the neck is through the roof. Use a dry lube inside the necks like the NECO kit or make your own like I did. Small steel shot or BB's with dry molly powder in a small plastic container. You’re just trying to get the dry lube in the case necks. This will also ensure the same seating depth and help prevent cold welding between the neck and bullet. What you're experiencing is normal with the annealing process.
 
#4
Re: Unexplainable high neck tension after annealing

I did not resize after annealing and many have stated this may be my problem. Looks like I need to change my process around some. Thanks for the input.
 
#7
Re: Unexplainable high neck tension after annealing

The 475 Tempilac is placed 1/4" below the shoulder. Therefore, it should be the proper temp at the shoulder. This tempilac is what came with the Hornaday kit.
 
#8
#9
Re: Unexplainable high neck tension after annealing

I have to agree with Roscoe on this. Don't water quench and six seconds or thereabouts in the flame is the name of the game depending on what you are using for flame. All you want to do is stress relieve in the 450°F range and not anneal.
There was a excellent article by a metallurgist in Precision Shooting July 1996 that explains it in great detail. This completely supports the ammo engineer's opinions I worked with who came from Frankford Arsenal.

If anyone would like a copy of this article I have it scanned and will gladly send you a copy attachment. Hit me with PM and I will send them out in batches. Takes a while to upload on dial up. Don't forget to put your email address in PM.
 
#10
Re: Unexplainable high neck tension after annealing

It depends entirely on where the 450-475 is *at*. I think a few of you are missing that the original poster is using the stuff from the Hornady kit, where you put it about 1/4" down from the shoulder - the idea being that by the time it reaches 475F *there*, the case mouth should be more at the required temperature 800F or so for annealing.

As for the neck tension... I found out the same thing not too long ago - I took some cases that had been cleaned via ultrasonic and then annealed them. The necks were very, very clean. So clean even a carbide expander ball had a hard time making it through w/ minimal neck tension. Ended up having to polish the snot out of the insides of the necks (0000 steel wool on a bore brush) to get everything working right. Definitely need to refine that process a bit more.
 
#11
Re: Unexplainable high neck tension after annealing

My guess:
I heat up brass bushings to remove them from bores all the time. I do this to shrink the bushing and help extraction. They never get to glowing temps. The necks you anneal should barely start to glow in dimm light. You are shrinking the I.D. of the neck is my guess. +1 Resize the neck after annealing.
 
#13
Re: Unexplainable high neck tension after annealing

Steve,

They never did on me when I used that system. Now that I've moved on to a Brass-O-Matic, it's a moot point for me. Along the way I also picked up some Tempilaq paint in various 'temps' from 300-900F and set about duplicating the experiment in the Brass-O-Matic instructions - the case head doesn't get even close to annealing temp during the process, and thats just air-cooled. One of the things I did notice was the higher temp paints near the case mouth were sometimes hard to read given the blackening from the torch - which may be why Hornady opted to measure a bit more indirectly, down out of the direct flame path. Makes a certain amount of sense...

Monte
 
#15
Re: Unexplainable high neck tension after annealing

I may be a simple guy from Sweden,

but annealing Lapua brass after 6x and in a 308 Win, well we all do it differently,

still I always anneal and then resize, when using bushings I find that I might have to go back a step or two, less rebound in the brass after an annealing.

Yes lubing is greatly needed necks are about as clean as they can get.

/Chris
 
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