NECK TENSION QUESTION.

[duck]

Can someone help me figure out why I'm getting what seems to be different neck tension with the same die.When i load some bullets load easy an some load hard.I'm loading a 6BR no turn neck using a Forster NS that sets my necks At .266outside .241 inside with blue box brass.An could this result in inconsistent groups?

 

[johara1]

Anneal and turn your necks to the same thickness.....jim

 

[SS427]

Annealing should fix the problem. I think it does impact group size, so when I get to where you are at I will sort my loaded rounds by how it feels when seating a bullet. Not very scientific and generally sort into only 3 groups.

 

[jlow]

Would it not be great if they make a tool that measues seating force?

 

[Erik Cortina]

Would it not be great if they make a tool that measues seating force?

They do! K&M makes a arbor press that uses a dial indicator to show the pressure needed to seat each bullet.

 

[jlow]

Thanks! Anybody used one?

 

[Va Jim]

Yes I do. It is a great tool. you can see exactly what the tension is and compare it from bullet to bullet. Eric and the others are right, Anneal you necks will cure a.lot of the irregularities of neck tension.

Va Jim

 

[jlow]

Do you see any corrolation between the neck tension you see on the gauge and the MV? I am assuming here that you weight your charges very accurately.

 

[walker2713]

So....annealing woithout turning the necks will accomplish the same thing?

I would've thought one should turn, then anneal.....

Am I missing something here?

Thanks

 

[amamnn]

Trying to set neck tension without knowing the neck wall thickness is like shooting blind. Annealing does nothing to make thickness uniform. Reaming sets the inside diameter only. Turning sets the outside only. Several of the retailers who cater to precision shooters offer tools to measure neck wall thickness. When you know the thickness, you know how much to shave off--- or out if you are reaming----then you can set the tension using a bushing die. Brushing the necks inside (after tumbling) will help uniform seating tension--which is not to be confused with actual neck tension as described above.

as an example: a .243 bullet outside diameter + .022 neck wall (.011 times 2 since there are two sides to the neck as affect the diameter) = .265"
So using a .263" bushing then yields .002" neck tension ...... annealed brass will keep these dimensions better than brass that has become springier with use........

Some bullets have a pressure ring--generally an extra .0005" added to the outside diameter. It does not really change much since you are trying to measure for uniformity. I've never had any of my measurements come out so close that the extra .0005" made a neck fail to chamber. Usually all my 6BR necks are at least .002 undersized or more when chambered in the currently fashionable "no turn" chambers..

Speaking of "no turn" I have yet to measure a box of 100 Lapua 6BR necks and find them all within .0015" I turn necks when they are out by .0015" or more old box, blue box same same, although the blue box necks are .001" thinner on average than the old box............I did buy 500 Norma 6BR cases that required almost no turning. I think I had to shave three... it's been a while.