Tight neck chamber

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by jon12, Mar 1, 2004.

  1. jon12

    jon12 Well-Known Member

    Messages:
    67
    Joined:
    Jan 24, 2004
    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.
     
  2. Guest

    Guest Guest

    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.
     
  3. Varmint Hunter

    Varmint Hunter Well-Known Member

    Messages:
    2,529
    Joined:
    Dec 26, 2001
    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
     
  4. LDHunter

    LDHunter Well-Known Member

    Messages:
    300
    Joined:
    Jun 21, 2001
    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]

    $bob$
     
  5. Guest

    Guest Guest

    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?
     
  6. Varmint Hunter

    Varmint Hunter Well-Known Member

    Messages:
    2,529
    Joined:
    Dec 26, 2001
    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]

    VH
     
  7. Ackley Man

    Ackley Man Well-Known Member

    Messages:
    98
    Joined:
    Mar 21, 2009
    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!
     
  8. Michael Eichele

    Michael Eichele Well-Known Member

    Messages:
    3,848
    Joined:
    Jan 6, 2003
    -Nevermind-
     
  9. mike33

    mike33 Well-Known Member

    Messages:
    898
    Joined:
    Dec 19, 2008
    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
     
  10. Ackley Man

    Ackley Man Well-Known Member

    Messages:
    98
    Joined:
    Mar 21, 2009
    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.
     
  11. TOM H

    TOM H Well-Known Member

    Messages:
    1,115
    Joined:
    Dec 24, 2001
    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.
     
  12. TracySes23

    TracySes23 Well-Known Member

    Messages:
    214
    Joined:
    Aug 16, 2012
    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!!
     
  13. AZShooter

    AZShooter Well-Known Member

    Messages:
    2,094
    Joined:
    Dec 12, 2005
    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.
     
  14. TracySes23

    TracySes23 Well-Known Member

    Messages:
    214
    Joined:
    Aug 16, 2012
    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.