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Tight neck chamber

 
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  #8  
Old 03-21-2009, 07:49 PM
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Re: Tight neck chamber

-Nevermind-
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Long range shooting is a process that ends with a result. Once you start to focus on the result (how bad your last shot was, how big the group is going to be, what your buck will score, what your match score is, what place you are in...) then you loose the capacity to focus on the process.
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  #9  
Old 03-21-2009, 10:21 PM
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Re: Tight neck chamber

Quote:
Originally Posted by Ackley Man View Post
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!
I had them when i was shooting bench rest 6ppc .262 neck. This was the best post i seen concerning the thread, well explained. I could not believe a standard round would chamber in a true tight neck chamber.
Mike
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  #10  
Old 03-22-2009, 03:02 AM
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Re: Tight neck chamber

I was in a rush when I posted the last reply and wanted to offer a couple other suggestions.

The purpose of a tight necked chamber is to keep the bullet in precise alignment with the bore. This can positively impact accurcy provided that bullet run-out is kept to an absolute minimum.

As previously stated, a tight necked chamber is not acceptable for standard hunting conditions. A couple of grains of sand can keep the round from chambering or cause a stuck case. Wose yet it could cause a live round to become stuck. If that should happen you would have a real mess on your hands. For hunting, a good alternative would be a minimum SAMI chamber neck. You don't have to turn necks and have the advantage of minimum clearance.

Another alternative for a tight necked chamber if you don't want to turn case necks is to buy a large supply of brass and cull it by using a neck mic for case neck thickness. Then make up a dummy round with one of the culls. With the dummy round in hand a gunsmith can order a special dimension reamer and cut the chamber neck so the loaded culls will maintain the 1 1/2 to 2 thousands clearance (per side). You then can have the benefits of a tight neck chamber without the labor pains of neck turning. The gunsmith may zing you for the price of the reamer but you would own it and could have it used in the future for other barrels.
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  #11  
Old 03-22-2009, 05:15 AM
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Re: Tight neck chamber

When I go into BR turning necks was part of the game most had two turners so it wasn't as slow as some make it out to be. We all use bushing type dies and you could get bushing in 1/2 tho size so you control neck tension that the part that most leave out. The amount of seating pressure for the bullet is one part of the accuracy game and thats the reason after I quit Br I still use bushing type dies and inline bullet seater.

Alot of guys I knew didn't like to turn necks always a place to buy prep brass so that wasn't a big deal and it didn't take alot of cases for the barrel life anyway. I always figured what I learned in BR made me a better reloader for the rifles I now shoot.
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  #12  
Old 06-21-2015, 01:21 PM
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Re: Tight neck chamber

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Originally Posted by jon12 View Post
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.
The single biggest reason I got a tight-necked chamber was to increase the longevity of my brass. The 2nd reason was the possibility of saving the time of not having to resize my brass every time which would save me a lot of time reloading. Since custom barrels are the norm for a tight-necked chamber, I assumed my accuracy would also be better if my skills were up to it. My loaded rounds measure .2480" - .2483", which seem to be perfect for me, since I've gotten everything I hoped for so far.
I now, no longer have to lubricate or resize my brass, I no longer need to clean the lube off my brass since there's none on it.
The inside bore of the brass is consistent enough for the grip the be consistent enough for my needs, without sizing it. Since I now use Lapua brass, I suspect the 100 cases I recently purchased may well last the remainder of my life. I rarely get out to the range more than once a week & I turned 74 in March.
Since I fabricated a special sub-collet (fits inside of a standard collet) on my Hardinge Lathe, I can turn cases in a minute or less per case for my Savage BR 22-250 w/the LRPV single shot action. I'm a happy camper!!
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  #13  
Old 06-21-2015, 05:09 PM
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Re: Tight neck chamber

Another reason for tight necked chambers.

Consistency in all aspects of handloading will help promote the very best accuracy that can be obtained from a rifle. Bullet release tension is important. It cannot be consistent if some case neck walls are thicker than others or if portions of a case neck are not the same thickness. If all cases have the same neck wall thickness then the bullet release will be more consistent shot to shot thereby helping to promote accuracy. It is part of a larger overall discipline.

I would like to mention that the individual can decide on how much neck clearance is right for their needs. It is dependent on the specs of the reamer and the original wall thickness of the chosen brass.

I have many rifles that I will use hunting with .003 or.004" per side neck wall clearance for bullet release. The tightest clearance I have hear of is .00035" per side. It was Virgil King in the article from Precision Shooting entitled The Secrets of the Houston Warehouse. It was chasing perfection in the BR game. A very interesting article!
Secrets of the Houston Warehouse

From article:
"Virgil did not size his case necks. With about .00035" clearance on all sides between the loaded round and chamber neck, the natural spring-back of the brass, in combination with his neck preparation, correctly gripped the bullets."

I made a 30 BR Long by plunging a 30 BR reamer approx. 1/2"deeper into the chamber to headspace as a 308. The design essentially grafts a 30 BR “top end” to the .308 Winchester case. The neck walls were turned to .0105" for a .0005" neck clearance per side. (1/2 a thousandth per side) I was able to reload without any sizing of the brass. There was some springback of the necks that held the bullet for single shot only. I could seat the bullets longer than the distance for contact with the lands and cam the bolt shut to have identical lands to ogive relationship. Some call this soft seating. Only thing I did was to carefully remove all carbon with fine steel wool and keep the chamber neck clean. I got the exact same accuracy as brass turned to .010" with more bullet release clearance of .001 per side that the necks had to be sized with a bushing die. It was fun but not a rifle I'd use for hunting.
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  #14  
Old 06-21-2015, 06:40 PM
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Re: Tight neck chamber

Quote:
Originally Posted by AZShooter View Post
Another reason for tight necked chambers.

I got the exact same accuracy as brass turned to .010" with more bullet release clearance of .001 per side that the necks had to be sized with a bushing die. It was fun but not a rifle I'd use for hunting.
I've never reamed a chamber before, but I've seen the specs & it appears as though the specs include the neck portion of the chamber. I may be wrong, but I suspect Shilen may use a chamber reamer for the 22-250 that reams the neck & chamber at the same time. Mine was chambered with a .250" neck diameter. They also have a slightly looser neck of .255" available. I checked the neck portion of my new barrel before I installed it on my action. It measured within .0001" of their .250" specs . So far I haven't had to resize my brass at all. Since it only expands .001" on a side, the spring back is perfect for my needs. Shooting a single shot rifle, I have no concerns about what tension I have on the bullet other than consistency. The tension I've measured using pin gauges tells me it's within .0005" from one case to another.
I've read that competition bench rest shooters often get 100 shots plus from each case.
To date, I've done no resizing at all on my case necks & they hold a bullet just fine. If I push hard enough with my thumb & first finger together tightly, I can make it move slightly, so I suspect the tension is okay.
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