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Tight neck chamber

 
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  #1  
Old 03-01-2004, 05:25 PM
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Join Date: Jan 2004
Posts: 67
Tight neck chamber

What exactly is a tight neck chamber, and what does it do? Why to people use them and what applications are they usually suited for? What are the advantages and what extra case preparation is required when loading cartriges for a tight neck chamber? Are there certain calibers where a tight neck chamber is more suited than others? Would this be a good idea for a long range hunting rifle in something like 7mm rem mag, why or why not?

Thanks.
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  #2  
Old 03-01-2004, 06:00 PM
 
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Re: Tight neck chamber

A tight neck chamber will cause you to have to neck trimm your brass which is the process of making the neck walls thiner.
the idea is to have the neck of you chamber just slightly larger than the neck of your loaded round , this will give the bullet a "straiter" start out of the case and into the barrel lands.

Alot of BR guys and varmint shooter have tightneck guns to help squeeze that little extra accuracy out of the gun.
The down side is that you SHOULD NOT try to shoot factory ammo out of this gun due to the tighter chamber squeezing the thivker unturned brass down on the bullet to tight , this can result in realy high chamber pressure which could be a realy bad deal.
Some guys swear by them and others swear at them , I personaly have never had one so I can't comment.
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  #3  
Old 03-01-2004, 06:54 PM
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Location: Long Island, New York
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Re: Tight neck chamber

A tight neck chamber allows you to closely fit your reloaded ammo to the custom chamber. Naturally, in a SAAMMI chamber the neck is quite loose so that all ammo will fit with room to spare. You can not make reloaded ammo larger in the neck to fit better so it is necessary to start with a "tight neck" chamber.
Brass can then be turned (thinning of the neck wall thickness)to a dimension that will result in ammo that has a neck diameter that is within a few thousandths of the chamber neck diameter. Fitted correctly, brass only expands about .002" upon firing which aids in accuracy and prevents the necks from being over expanded. Cases normally require VERY little resizing. The neck turning operation also provides for very uniform neck wall thickness which also aids in accuracy.

I have never seen factory ammo that would fit in the chamber of a tight neck rifle. But I guess one should never say NEVER. Typically, custom barrels with tight neck chambers have the neck diameter engraved into the barrel right next to the cartridge designation, but not always.

In my experience, a tight neck chamber is a bad idea for a hunting rifle. All work and no benefit. The only exception would be in a looongrange hunting rifle, particularely where the targets are small varmints.

VH
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  #4  
Old 03-03-2004, 02:23 PM
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Join Date: Jun 2001
Location: NW Florida Piney Woods
Posts: 237
Re: Tight neck chamber

Another BIG advantage of a tight necked chamber is that your expensive and carefully matched brass will last much longer due to the chamber neck limiting brass neck expansion.

Less expansion = less reforming stress = less aggressive working of the brass = longer brass life. [img]images/icons/grin.gif[/img]

$bob$
__________________
If it's long it can't be wrong... LDHunter (Long Distance Hunter) from the Piney Woods of NW Florida. I hunt clearcuts for scrawny whitetails... ;)
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  #5  
Old 03-03-2004, 03:31 PM
 
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Re: Tight neck chamber

If I neck down a 30-06 to 270 how much thicker will the necks get. Can I than neck turn to cleanup the necks and have the case neck fit the factory chamber a little better. Would this be kinda like a redneck tight neck chamber or am I wasting my time?
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  #6  
Old 03-03-2004, 04:36 PM
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Join Date: Dec 2001
Location: Long Island, New York
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Re: Tight neck chamber

There may be other dimensional considerations to that conversion. The 270 has a longer overall cartridge length and , I believe, a longer base to shoulder length.
Assuming that you corrected these dimensions, you would also have to know what the neck diameter of your factory chamber was so that you could make certain that your finished ammo left adequate room for case neck expansion.
Given these two considerations, I do not see why you could not do as you suggested. Would it be worth the trouble; I seriously doubt it.
Several months age, one of the shooting magazines did an article on doing this type of brass work for a factory chambered 22-250 rifle. I forget what case they used as the parent case for the project but they were able to rework the case and ended up with a very thick case neck which was turned down to closely fit the factory 22-250 chamber neck.
Yes, all things are possible. [img]images/icons/wink.gif[/img]

VH
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  #7  
Old 03-21-2009, 06:05 PM
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Join Date: Mar 2009
Posts: 98
Re: Tight neck chamber

This is kind of a strange thread going from quesitons & comments concerning tight necked chamber to forming .270 Win brass from '06!

I have several tight neck chambered guns. First, a tight neck chamber is, as previously stated in the thread, a chamber with a neck dimension that is less than the minimum SAMI spec. Accordingly, it would be impossible to chamber a factory loaded round or factory brass into a tight necked chamber unless the so called tight necked chamber was not in reality a tight neck. A gun with a true tight necked chamber will be so marked on the receiver by the gunsmith that did the chambering - unless he was an idiot. To prep brass for a tight necked chamber you must use a neck turning tool that is really just a mini hand held lathe. Some machinest types have actually made some tooling so they can neck turn in a standard lathe. Neck turning is a slow process and constant measuring with a neck mic must be done to insure that you have 1 1/2 to 2 thousands clearance between the brass neck and the neck portion of the chamber. Accordingly, it would be a bad idea to try and use a tight necked gun for general hunting as a few grains of sand to prevent chambering. I don't believe tight neck chamber prolong case life since the necks are thinned and have a propensity to crack after repeated firings. Another thing that is necessary with a tight neck chamber is to body size and shoulder bump the cases about every five firings with neck sizing only in between. Don't get the thinking about case forming 06 to 270. Cant you still by 270? Why chance on overworking the brass and invite a case failure? Nuff Sed!
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