neck tension

col48

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Feb 17, 2006
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261
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Nottingham, UK
hi all
i have just miced my brass necks and they come up at 13thou so i have doubled it = 26 thou + my bullet 243 = 269
at the present time i am running a 265 bush,so i have 4 thou of neck tension,what is the best neck tension to run on.i was thinking down the lines of getting a 267 bush and go with 2 thou as it is a fox round and will need to be chambered and un chambered. will 2 thou be OK.i don't have a mag only a bullet holder on the stock.(uncle Mick's)
what tension do you lot prefer.or will 4 thou be ok.
is it worth changing it??????? /ubbthreads/images/graemlins/confused.gif
thanks
Colin.
 

Centre Punch

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Oct 29, 2004
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Location
Northamptonshire England
Hi Col its me again,
I am using a .267 bush for my Ackley but i have done a light .0005 neck clean up.
My loaded round dimension before turning was .270, so after turning i have .0025 of neck tension, works well even when unloading a round that is .005 into the lands.

Ian.
 

Bart B

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Dec 25, 2005
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2,763
An old rule of thumb on neck tension to grip the bullet firm enough for just about all uses is to have the neck sizing part of the die (bushing, or whatever) 1% smaller than a loaded round neck's diameter. If your loaded rounds have a .269-inch neck diameter, then the neck sizing part of the die should be .26631-inch to follow this rule.

Your choice of .267-inch for the bushing is great. Depending on the ductility of your case necks, you may need to use a .268-inch bushing if they don't spring back enough; or a .266-inch one if the neck springs back too much.
 

col48

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Feb 17, 2006
Messages
261
Location
Nottingham, UK
[ QUOTE ]
An old rule of thumb on neck tension to grip the bullet firm enough for just about all uses is to have the neck sizing part of the die (bushing, or whatever) 1% smaller than a loaded round neck's diameter. If your loaded rounds have a .269-inch neck diameter, then the neck sizing part of the die should be .26631-inch to follow this rule.

Your choice of .267-inch for the bushing is great. Depending on the ductility of your case necks, you may need to use a .268-inch bushing if they don't spring back enough; or a .266-inch one if the spring back too much.

[/ QUOTE ]

so Bart you are saying i have to much neck tension on my cases. will this make 4 in to .3 then 1 away at .5

02052006092-001.jpg


02052006093-001.jpg


i do not think the flyer's where made by the driver (me)
sorry for the bad pic i only have a phone one.
can you shed any light on the matter.
if you look at the groups they look exactly the same.
and they measure
group 1
the 4 on there own .328 with the 1 out .657
group 2
the 4 on there own .305 with the one out .594
so what you think /ubbthreads/images/graemlins/confused.gif
 

abinok

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Nov 25, 2004
Messages
877
[ QUOTE ]
is it worth changing it???????

[/ QUOTE ]

Maybe, is it shooting? /ubbthreads/images/graemlins/smile.gif
I usually start at .003" if its a mag fed rifle, and .001 if its a single shot, then adjust neck tension as a final element of the process when tuneing a load. HOWEVER: if its shooting at .004", why fix whats not broken?
 

Bart B

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Dec 25, 2005
Messages
2,763
[ QUOTE ]
so Bart you are saying i have to much neck tension on my cases. will this make 4 in to .3 then 1 away at .5

[/ QUOTE ]No, they're about right if your accuracy is good.
 

col48

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Joined
Feb 17, 2006
Messages
261
Location
Nottingham, UK
[ QUOTE ]
[ QUOTE ]
is it worth changing it???????

[/ QUOTE ]

Maybe, is it shooting? /ubbthreads/images/graemlins/smile.gif
I usually start at .003" if its a mag fed rifle, and .001 if its a single shot, then adjust neck tension as a final element of the process when tuneing a load. HOWEVER: if its shooting at .004", why fix whats not broken?

[/ QUOTE ]

hi abinok
would you think that the 1 away is driver error??????
its just bugging me,they should all be in the same ball park with the stick I'm using. /ubbthreads/images/graemlins/confused.gif

i am going to go up in powder and try some different neck tensions .1 .2 and .3 just to see if i can get that one in a bit more. then go out and shoot some data.
unless anyone can cast some light on the one away
 

col48

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Joined
Feb 17, 2006
Messages
261
Location
Nottingham, UK
[ QUOTE ]
[ QUOTE ]
so Bart you are saying i have to much neck tension on my cases. will this make 4 in to .3 then 1 away at .5

[/ QUOTE ]No, they're about right if your accuracy is good.

[/ QUOTE ]

so what about the one away,what can i do to get this in the same ball park
thanks
Colin
 

Bart B

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Dec 25, 2005
Messages
2,763
[ QUOTE ]
so what about the one away,what can i do to get this in the same ball park?

[/ QUOTE ]First, you gotta find out why it went there. There are no fliers in the accuracy game. Every bullet went through the target exactly where it was supposed to based on how the round was shaped (cartridge dimensions), loaded (positioned in the chamber), shot (how the rifle was held during the time the sear released the firing pin and when the bullet left the barrel) and aimed (where the sights were aligned on the target when the bullet left the barrel). Somewhere in each of these four areas, something went a bit astray. Unless one knows which one, it's kinda hard to tell why it went there.

Sorry, but I don't have an answer. We both need more data on that "flier" to compare against the others; then we'd know why it went there.
 
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