Neck thickness experiment?

M

muslmutt

Guest
One day I was trimming brass and placing that freshly trimmed brass in a loading block prior to chamfering or deburring. I noticed when I looked straight down on that brass in the loading block I could clearly see that some were significantly thicker on one side, thin on one side, thick or thin all the way around, or even. I do not have a neck thickness gauge. Am I seeing what I think I am seeing? Is this a viable and/or legitimate way of sorting brass with out having to buy a neck thickness gague? I am not planning on competeting. I just want to see how accurate I can get my factory/hybred rifes to shoot.
Thanks.
Matt.
 
Matt......

go to ebay and type in "tube micrometer".

You will get several very good mics that will enable you to answer your own question.

If you are seeing differences with the naked eye, then you need to know exactly how far out of wack those case necks are.

Using calipers on a round surface like that is not very accurate.
 
Matt,

On one occasion when I trimmed some tough Aussie exmilitary brass with a cutter that was a tad dull, the brass peined over here & there rather than cut clean. That gave the impression that the brass was way thicker on some parts of the neck than others. Once it was deburred, it looked fine.

Any chance that's the sort of thing you saw?

John
 
I think John is right, you are seeing the burr that rises when you trim. Knock it off and see how they look.
 
I thought that might be what I was seeing, but I was thinking why was there more on one side if it was not really thicker there?
I remember when midway's prices included shipping. I have not bought much from them since they changed.
 
Jay said:
I went to Miday and put one in my "cart". Cost for "Priority Mail", the cheapest option, was $13.60! That is 45% of the cost of the item. Unacceptable ripoff.

Bye, bye Midway.
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Jay, that's the very reason I no longer use Midway unless it's an emergency or I can't find the item anywhere else. They have gone slap crazy with s/h charges. I shot them an email about it but never got a reply. Imagine that.

I use Powder Valley now for primers, powder, brass, and bullets or use the local gun store to order it for me.
 
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muslmutt said:
I thought that might be what I was seeing, but I was thinking why was there more on one side if it was not really thicker there?
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I've seen the same thing on newly trimmed cases before they were chamfered, and yes it can occur. Check them after they're chamfered and you likely won't be able to see the difference. Sometimes the way the light shines on something causes a sort of optical illusion too.

I did see some early (1960's) LC headstamped 5.56x45 (223) military cases that were terribly uneven. The necks were visibly non-uniform, about twice as thick on one side as the other. Lots of the flash holes were WAY off center too. Most commercial and later military brass is a LOT more uniform.
 
muslmutt said:
One day I was trimming brass and placing that freshly trimmed brass in a loading block prior to chamfering or deburring. I noticed when I looked straight down on that brass in the loading block I could clearly see that some were significantly thicker on one side, thin on one side, thick or thin all the way around, or even. I do not have a neck thickness gauge. Am I seeing what I think I am seeing? Is this a viable and/or legitimate way of sorting brass with out having to buy a neck thickness gague? I am not planning on competeting. I just want to see how accurate I can get my factory/hybred rifes to shoot.
Thanks.
Matt.
Click to expand...

Matt
You are indeed seeing a variance in neck thickness
THis is the main reason that BenchRest shooters have been outside neck turning their brass for Many Many years. This is not a new issue, although some brands such as Lapua will have a more consistant neck thickness.

PS I believe that consistant neck tension is one of the keys to loading ammo capable of shooting teen (sube .200 inch) aggs. And you can't get good consistant neck tension without consistant neck thickness.
If you are a machinest you can use a ball micrometer to measure neck thickness.

TED
 
Case necks

I've also seen necks with thick and thin areas, without using magnification. Verified what I thought I saw with my tubing mic., and found as much as .004" variation, with some of the "big name" brands. Try to use Lapua and Norma when possible, if not, will measure and segregate, .001" being my limit.
 
On some Remington 25-06 Brass I have, the variation is a tad more than .005.
IF you just say out loud that you can see a .004 or .005 difference, it seems preposterous, but you really can see it.
Ted
 
One guy had made a post w/ pics that showed what was basically a block he had cut a V in. He would place a loaded round in the V rotate the cartridge while he looked straight at the bullet tip to check for concentricity. If you try this you may be impressed with how little variance you can see with the naked eye.
 
I shoot a Savage 22-250 and try to eliminate all the variables when it comes to loading. To this end, I use a Lee collet neck sizer because it indexes on the INside of the case mouth, not on the outside like most of the others neck sizers. I also trim to uniform length, and when done, trim the necks to uniform thickness with a K&M tool (only on my once fired). Almost ALL the case necks I've trimmed are slightly thicker on one side than the other...to a greater or lesser degree...:D
 
I never have any problem getting up a $200 or $300 when I need stuff from Midway :D. This makes the shipping inconsequential. Get the ball mic.
 
crb said:
I never have any problem getting up a $200 or $300 when I need stuff from Midway :D. This makes the shipping inconsequential. Get the ball mic.
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crb, I never have any proplem getting up a $200 or $300 order for Midway either.

My problem is getting the $200 or $300 to pay for it!:D
 
Im sure you know already that the way to get rid of the variation in neck thickness is to run the brass up an expandron mandral which will put all the deformity on the outside of the neck. Then turn the brass with a neck turning tool of your choice (I like the K&M neck turning tool). After you do that you will have perfectly even necks. It is important enough that I even do it on my factory guns with loose chambers. It helps with even neck tension, loaded round concentricity, and an even expansion of the brass.
 
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