Neck tension

[slingshot]

How do we all do it when reloading

[obsessed1]

For my lighter recoiling hunting rifles not much except trimming my case length the same. On heavier recoiling hunting rounds trim cases and crimp with Lee factory die. On my precision loads I measure neck wall thickness, turn and real necks, trim to length, and crimp with Lee factory crimp. I used to crimp every thing and turn necks on all my rounds after 5 reloads. But for hunting accuracy (moa +- a scoach) my record data shows the accuracy gain is not at all worth the effort. For my long range guns though it has proven a worthwhile effort.

[260 Rem]

For factory chambers which generally have generous clearance, I use the S type Redding sizer die which uses an appropriate diameter bushing ... to get .002" "tension". For chambers that have neck diameters cut under SAAMI spec, I also use an outside neck turner to make sure I have .002" neck tension, and at least .001" radial clearance between the outside of the (loaded) neck and the chamber wall.

[Bushrat]

They say that it is near impossible to get more than .002" neck tension. You can set up for .004" or .008" or whatever you want your neck sized under bullet diameter but when you seat the bullet it stretches the neck circumference to fit in there, if you remove the bullet without firing just by pulling it, your neck diameter will on average only spring/shrink back on average about .002" , it won't go all the way back to your .004" or .008" desired 'neck tension'. Measuring case neck diameter and bullet diameter and recording the difference is a measurement alright but it is a poor way to measure neck tension, measuring .002" on one piece of brass might give you, lets say 12 lbs of neck tension on a wore out piece of brass and maybe 25lbs on a new case. It is not a measure at all, it doesn't take into account how much a particular batch of brass will stretch due to annealing, the amount of work hardening, malleability and stretch, all these vary among brands, neck thickness, type of brass alloy and amount of work hardening or annealing it has received. To measure actual neck tension you need equipment that measures the actual weight of pull needed to extract a bullet from the case neck.

[elkhunter11]

I also use the Redding Type S neck bushing dies, and try for .002" of neck tension.

[Mateo]

Bushrat has a solid point. Annealing is so important to consistant neck tension. Seating a bullet further out so less of the neck is holding the bullet changes neck tension quite a bit.

[260 Rem]

I'll use an example of one round I shoot. 308 Win fired in a chamber with .340 NK using Lapua Blue box brass. I use a bushing to resize the neck to measure .336, and when I seat the bullet, the OD neck measurement is .338 which is then fired in the .340 NK. I call that .002 NK tension. If I used my conventional Hornady resize die, it would reduce the outside neck case diameter to .334 which would still result in a measurement of .338 when the bullet is seated. I would call that .004 NK tension. Unless really hotting up loads, I would not see accuracy difference before a dozen firings, and at that point, I would consider annealing.

[RAMPAGE]

bushrat couldn't of explained it any better

[catnthehat]

I have a few match rifles that I use bushing dies with , but most of my rifle cartridges get loaded with either full length dies or collet dies .
Neck tension difference us something that I have found is not one of the variables that will make a significant difference in my shooting when using must if my rifles so I generally don't worry about it unless I see an obvious lack of tension when I first check the cases .

Cat

[ROA]

I have found that annealing has had a positive effect on every rifle I have tried it in, even in hunting rifles that struggle to keep them in 2" at 100 yards. As for the amount of neck tension needed for best accuracy that needs to be experimented with for each rifle. My current findings is more neck tension is better for rifles with long throats especially with secant ojive bullets, but I am sure sooner or later I will come a cross one where this is not the case.

[Bushrat]

Inconsistent neck tension is one of the reasons seating a bullet on the lands will often help a rifle shoot better, it takes away the neck tension factor to some degree and uses the jam of the bullet in the lands as the resistance for the bullet leaving the case as opposed to neck tension. It can be far more consistent form of resistance. Problem with neck tension is that it may be pressure expanding the case causing the bullet to be released in which case when a bullet is jammed is I think what happens and it wouldn't matter what neck tension your running, or is it the bullet being pushed out of the case before it expands to fill the chamber which is what I think happens when there is a jump to the lands. Then again factory crimped ammo and crimped hand loads change and increase neck tension, hard to say what happens there. So many variables for us to consider no two loads and no two rifles are the same so we get to experiment and find what works for a particular gun and load. The rule of thumb is there is no rule of thumb for every rifle.