- August 6, 2016 at 1:00 pm #29266
This is a facet of cartridge design I have never read anything about. I believed that for cast bullet use, thin necks are desirable because it reduces neck tension on the bullet across the board, hard to soft. Thus, I designed the 35XCB with a neck about the same thickness as the 30-30 cartridge.
There were other reasons I did this such as reducing the amount that the brass is worked by the modified 35 Whelen dies, and guaranteeing that the necks could be cleaned up completely when they were turned.
There was a ton of measurement and balancing of tolerances and testing that went into it, but the end result was a neck that was .011 thick nominal.
It crossed my mind recently, that maybe the neck thickness has a dynamic roll to play in rifle accuracy, and I have never read any opinion on this (if I did, I missed it).
Have any of you gents run across an opinion on this subject?
- August 6, 2016 at 3:31 pm #29268uber7mmParticipant
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Neck thickness is a parse subject. I have read .011″, 012″ are desired thickness range on other forums.
‘I turn mine to .012″ ‘, might not be a qualified opinion…. I did find it on the web: “caveat emptor”.
After years of reloading & shooting the same cases, the necks do wear out. I’ve retired some cases that had necks so thin the expander plug gave no resistance when sizing. Regrettably for this conversation, I never kept any records on the subject.
We want proper and consistent neck tension. Too thin of a neck, and the case won’t hold the bullet properly and accuracy will suffer. Too thick, (in the instance of cutting down cases) and there will be issues sizing and seating the bullet during reloading, and the potentially resizing a soft lead bullet smaller than desired. There can also be potential chambering issues in the field. These examples I’ve experienced.
Neck thickness and tension is an interesting subject. These are my experiences on the subject and would like to hear others.
- August 6, 2016 at 4:59 pm #29270
The question I have is, all things being perfect (as they will be when I am loading) IE: perfectly concentric, perfectly straight, perfectly annealed etc etc eye, does the neck thickness have an effect on accuracy?
Assuming the chamber is made for it, and everything fits perfectly, is .010 thick necks good for a certain pressure range/bullet hardness, while .016 thick necks are ideal for another????
have you ever read about this being discussed by one who has made reliable testing their life’s mission?
There are a lot of people who do not test their theories correctly/thouroughly, and as a result they seldom have a firm grasp on what’s actually going on.
For instance, I wish Brian Litz had written about this?
- August 8, 2016 at 3:02 pm #29319oldblinddogParticipant
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Has anyone discussed this with a factory tech.? Hornady comes to mind as a place to start. I’ve taken their tour and their willingness to discuss things surprised me. The guys in the basement that are shooting pressure guns under the parking lot are the ones you want to talk to.
- August 10, 2016 at 6:02 pm #29369popperParticipant
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is .010 thick necks good for a certain pressure range/bullet hardness, while .016 thick necks are ideal for another????
A neck radial expansion of 0.002″ gives a circumference expansion of 0.006″. That is why we get neck splits and probably what the case designers aim for. We assume the barrel neck gives another very fast 0.002-3 expansion so the neck gets a double whammy. Plus the field abuse the case gets. Mil ammo with a thicker neck for MG chambering, where the 30/30 is thin. I doubt it effects accuracy.
- August 13, 2016 at 7:07 pm #29433
Yes I have seen discussion of this many times. There are two basic thoughts on it one side says yes, it makes a difference, the other says no it doesn’t. The no camp says all that matters is that the tension is uniform and a tight neck is truly not needed.
- August 14, 2016 at 2:39 am #29441
I happen to agree. Within a given neck thickness, uniformity is important. Of course, there are other factors involved suck as internal surface finish and cleanliness, but for this discussion, let’s assume these factors are perfectly established.
Also, there’s the issue of the fit of the neck to the chamber. Let’s assume that also is in a nice comfortable spot.
My thought is, that there may be a point where the necks are too thin to give a consistent release to the bullet?
Perhaps a thin neck might be so weak that the only way to get a consistent release of the bullet would be to have exactly the right powder with exactly identical hardness?
Assuming this issue were exacerbated by designing a cartridge with a large diameter bullet intended to function at 45,000psi, with a .011 thick neck, how much error could it possibly induce into the accuracy equation?
- August 14, 2016 at 2:53 am #29442
Thin necks have a tendency to lose tension without proper annealing however given enough time even repeated annealing will not reset the neck’s property to provide consistent tension.
Tight necks in the chamber is a neck turn solution that many despise. Regular firing without cleaning could cause problems as the carbon would build to the point hat a tight neck would behave way less desirable.
- August 14, 2016 at 2:59 am #29443
One thing that Bill Alexander attempted to do was borrow from the the Lee- Enfield with the Grendal was a compound angle throat to center the bullet. because he was doing so in a Semi such as the AR he had to allow a bit of tolerance there for functioning shape. Later Les Baer after falling out with AA designed the 6.5 LBC which had a tighter neck.
Many said the average group size of the LBC was improved
- August 14, 2016 at 3:12 am #29444
Interesting thought. I forgot about that.
Still, that was a relatively small improvement.
definitely something to ponder over.
- August 14, 2016 at 3:39 am #29445
While not exactly dealing with necks, give this a read Tim (http://www.allaboutenfields.co.nz/links-resouces/articles/articles-of-interest/)
But like mining for gold sometimes you have to pan for the nuggets inside the article is has several little blips into your question.
- August 14, 2016 at 10:16 pm #29455popperParticipant
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function at 45,000psi, with a .011 thick neck, how much error could it possibly induce into the accuracy equation?
Tensile strength is measured in psi but it’s the actual force that does the work., i.e. thicker neck is stronger, duh. So when the circumference stretches, and metallurgy allows a weaker spot you could develop a crack/split. IMHO this is so far into the weeds as it doesn’t count.
- August 16, 2016 at 2:48 am #29481
A lot of the older cases did use the thinner necks.
25-20 Single Shot .275″
25-21 Stevens .280″
25-25 Stevens .282″
30-30 as you mentioned earlier with a .330″
30-30 Wesson uses a .001″ thinner than the 30-30 Winchester .329″.
30-40 Krag .338″
30-40 Wesson .329″
30-78 Single Shot .331″
32 Ideal .344″,
35-30 Maynard (1873) neck dia is .397″
35-30 Maynard (1882) neck dia is now listed at .395″ a thousand thinner than 1873
35-40 Maynard (1882) neck dia is .390″ .
35 Winchester Self Loading the neck dia was .374″
351 Winchester Self Loading was .373″ the 351 WSL was to replace the 35 WSL in 1907
45-70 Govt .480″
45-70 Sharps .481″
I’ll leave you to your math LOL Hope this helps (source Handloaders Manual of cartridge conversations)
- September 4, 2016 at 5:01 am #29870uber7mmParticipant
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I searched the internet regarding neck diameter, regrettably not much:
Summary: If not shooting 1000yds, you probably won’t see the difference. Where’s the empirical evidence?
The need to neck size after .0015″ variance.
Shooting and Loading the 6.5 Credmore, neck run out analysis mentioned.
- September 4, 2016 at 12:08 pm #29871
I suppose I was worried that necks designed too thin would give inconsistent bullet release.
- September 5, 2016 at 1:16 pm #29887bjornbModerator
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Since I know you started this thread partially due to the issues we have had with my lightweight 35 XCB rifle “Eskimo Queen”, I’d like to point out that when shooting Felix, my 20 lbs. target rifle also chambered in 35 XCB, using the SAME cases (turned to .010), I always got excellent accuracy with both cast and jacketed.
Thus I believe that we have correctly narrowed the problem down to a janky barrel (a very whippy Douglas), and that the new Krieger (to be delivered March 2017ðŸ˜©) will solve our issues.
- September 5, 2016 at 2:27 pm #29891
I had forgotten about that rifle!
That certainly answers the question then!
That at being the case, the only possibility is a janky barrel. Douglass has sent us a bad one.
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