G'day
Well it seems today is the day for asking all those questions that were in the back of your mind, so here goes.!!
I dont get the whole neck turning busines.??
Why is it so important to neck turn for accuracy.??
Is it so the projectile is in the exact centre of the case to start with or does it have some effect on how tight the space is between the outer edge of the case neck and chamber edge.??
would your cases not form to the chamber dimensions when fired anyway.??
Is it to thin the neck from growing in thickness with all the brass forcing forward when it is fired, I know we trim length but is this the thinning process.??
I may not be all that clear about this but tell me in basic terms what it does and why it is done.
Regards
Damien Webb.
PS I know its probably out there on the net some where but I dont want to read a heap of pages I just want to be told.
Neck turning.????
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native hunter
- .270 Winchester
- Posts: 1435
- Joined: Mon Jul 10, 2006 1:07 pm
- Favourite Cartridge: .22lr
- Location: Ballina
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Ackley Improved
- 6mm Dasher
- Posts: 1898
- Joined: Wed Aug 09, 2006 12:24 pm
- Location: Albury
Right.
If you looked at the neck of a case the amount of brass around the radius would not be consistant. That being brass in one area maybe thicker than another. By running a case over a expander mandrel or button, you are making the inside of the neck uniform. That inconsistant brass on the neck is now pushed to the outside, so it will have high and low spots.
By turning the outside of the case, this eliminates the inconsistant thickness of the brass on the necks.
So what does this mean. Well, if brass is thicker on on side of the neck, then the tension will be greater on that side holding the projectile, which degrades accuracy because of the inconsistancies (every bullets neck tension will be different).
It also allows you to get the right amount of neck clearance to the chamber. i.e. if your neck dimension is 0.269, then you turn your brass to 0.267, which has benifits in itself.
Neck turning is really good with crap brass, but with the likes of Lapua, specially the 6mmBR stuff, straight out of the box is fine!
It is non-fun work neck turning, but even if it makes the slightest differnt on the paper, its good enough for me.
Might have missed something.. to tired....
Cheers
AI
If you looked at the neck of a case the amount of brass around the radius would not be consistant. That being brass in one area maybe thicker than another. By running a case over a expander mandrel or button, you are making the inside of the neck uniform. That inconsistant brass on the neck is now pushed to the outside, so it will have high and low spots.
By turning the outside of the case, this eliminates the inconsistant thickness of the brass on the necks.
So what does this mean. Well, if brass is thicker on on side of the neck, then the tension will be greater on that side holding the projectile, which degrades accuracy because of the inconsistancies (every bullets neck tension will be different).
It also allows you to get the right amount of neck clearance to the chamber. i.e. if your neck dimension is 0.269, then you turn your brass to 0.267, which has benifits in itself.
Neck turning is really good with crap brass, but with the likes of Lapua, specially the 6mmBR stuff, straight out of the box is fine!
It is non-fun work neck turning, but even if it makes the slightest differnt on the paper, its good enough for me.
Might have missed something.. to tired....
Cheers
AI
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glenn asher
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Ned Kelly
- .270 Winchester
- Posts: 1277
- Joined: Tue Oct 31, 2006 6:39 am
- Favourite Cartridge: 6PPC
- Location: Macedon Ranges Vic
G'Day All,
essentially you are trying to have consistent neck tension as AI said but also to align the bullet exactly with the centreline of the barrel.
Bullet alignement is another critical part of the accuracy equation.
However in factory chambers, you would only neck turn to clean up/cut about 70-80% of the neck surface , mainly due to the sloppy fit of the case. This is purely to try and improve neck tension consistency on the bullet.
Remember, if it is a factory chamber there is no guarantee of chamber to bore centre alignment due to manufacturing tolerances. You could only be certain of chamber to bore alignment with a custom job from a reputable gunsmith. And then you can specify a tight neck or preferably a no turn neck chamber reamer for your re-barrel job if you want to.
Occaisionally, when neck turned cases are fired in a chamber with a sloppy neck, the case will expand to fit. So that when resized, you will have a second shoulder somewhere along the neck (usually with Wilson dies)
This can help with case alignment in the chamber (but not necessarily with the bore centreline) but I suspect it will cause excessive working of the brass at this point, which is not good for case life. My 22.250 with 100% neck turned W-W cases did this and lasted about 10 firings before the primer pockets expanded too much, so I cannot say about the effect on the necks from this double shoulder.
Essentially for a varminting rifle, I personally neck turn for a 80% clean up and that is because I have .224 & 6mm neck turning tools. I would then use Lapua brass and quality factory made reloading dies and leave the custom dies to target shooters who need the accuracy. Save your penny's for a new barrel or better quality scope, thats the easiest way to improve your accuracy!
I would not consider it for a general hunting rifle as i can tune the reload to get more benefit to me than neck turning ever would.
Hope this helps
Cheerio Ned
essentially you are trying to have consistent neck tension as AI said but also to align the bullet exactly with the centreline of the barrel.
Bullet alignement is another critical part of the accuracy equation.
However in factory chambers, you would only neck turn to clean up/cut about 70-80% of the neck surface , mainly due to the sloppy fit of the case. This is purely to try and improve neck tension consistency on the bullet.
Remember, if it is a factory chamber there is no guarantee of chamber to bore centre alignment due to manufacturing tolerances. You could only be certain of chamber to bore alignment with a custom job from a reputable gunsmith. And then you can specify a tight neck or preferably a no turn neck chamber reamer for your re-barrel job if you want to.
Occaisionally, when neck turned cases are fired in a chamber with a sloppy neck, the case will expand to fit. So that when resized, you will have a second shoulder somewhere along the neck (usually with Wilson dies)
This can help with case alignment in the chamber (but not necessarily with the bore centreline) but I suspect it will cause excessive working of the brass at this point, which is not good for case life. My 22.250 with 100% neck turned W-W cases did this and lasted about 10 firings before the primer pockets expanded too much, so I cannot say about the effect on the necks from this double shoulder.
Essentially for a varminting rifle, I personally neck turn for a 80% clean up and that is because I have .224 & 6mm neck turning tools. I would then use Lapua brass and quality factory made reloading dies and leave the custom dies to target shooters who need the accuracy. Save your penny's for a new barrel or better quality scope, thats the easiest way to improve your accuracy!
I would not consider it for a general hunting rifle as i can tune the reload to get more benefit to me than neck turning ever would.
Hope this helps
Cheerio Ned
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native hunter
- .270 Winchester
- Posts: 1435
- Joined: Mon Jul 10, 2006 1:07 pm
- Favourite Cartridge: .22lr
- Location: Ballina
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Gavin NZ