Determining best Neck Tension

[GunnyUSMC]

I am wondering how other reloaders come to the conclusion as to how much neck tension is needed.

I am very familiar with how to determine bushing size, mandrel size and etc. For example, I have sized my necks to .0010, .0015, and .002. If I am putting together hot loads, I typically like less neck tension so as to not build up too much chamber pressure. If I am building magazine fed loads, i like a little more neck tension. Sometimes, i might put a little more neck tension to increase my MV without increasing powder.

Any other thoughts?

 

[spife7980]

I just use a turning arbor and run with it.

To determine best will require you to test.

 

[Marine52]

yes test but first start with good brass like lapua or Alpha. I tried .0005 to .004 and found .002 to be optimal on my FTR rifles. However, consistency is key and annealing provides the consistency in tension. My biggest breakthrough came with the use of neolube. I dip the neck in powdered graphite before running a .306 mandrel on my 308 lapua brass. Before priming I use a Q-tip to apply neolube inside the neck. I seat with an arbor press with gauge and now all of my bullets seat right at 30 lbs. very little deviation.

 

[RegionRat]

If I am putting together hot loads, I typically like less neck tension so as to not build up too much chamber pressure.

Just food for thought.

When we start new recruits in this field, we start them with lots of old history including black powder, muzzle loading, paper cartridge, etc. but notably they also do some straight walled pistol cartridges. The low pressure ones first, then the ones like 357 and 44 mag.

On that path, they get to see the effects of low to high "neck tension" and even topics like crimps or sealants on performance.

In an industrial ballistics lab we have the advantage of being able to show them the effects on seating and pull forces, all while they get to watch the shot pattern performance from a shooting machine.

Later comes the bottleneck centerfire stuff. By then they have already got the hang of low to high bullet retention forces and the effects on the pressure traces, velocity stats, and accuracy.

I would never tell you that low "neck tension" isn't correct for your "hot loads", but only to encourage you to keep an open mind that the context matters and most context with high powered rifles running higher pressure recipes will tend to do better with more bullet retention that allows the pressure to build sooner and more effectively ignite a larger slower powder charge. Context always matters.

Let the target and your velocity stats guide you, but always keep the safety of the context in the front of the line. Weak ammo is okay in a controlled range setting, but can be dangerous in a stressful dynamic setting or when there is the possibility of rough handling or set-back. YMMV

ETA: Semper Fi !

 

[memilanuk]

consistency is key and annealing provides the consistency in tension. My biggest breakthrough came with the use of neolube.

Similar here. For a very long time (too long) I avoided messing with inside neck lube like the plague. Same with brushing case necks Too messy, too slow, yada yada.

The thing is... they work. The condition of the neck ID has a lot more effect on consistency of seating than neck tension, up to a point. With smoother necks, you can work with higher neck tensions - or not - without adversely affecting your bullet seating.

As mentioned before, the bullets will tell you what works best in your gun. But being able to seat the bullets more smoothly may change how your accuracy responds to higher neck tension - or not. Try it and find out.

 

[GunnyUSMC]

would never tell you that low "neck tension" isn't correct for your "hot loads", but only to encourage you to keep an open mind that the context matters and most context with high powered rifles running higher pressure recipes will tend to do better with more bullet retention that allows the pressure to build sooner and more effectively ignite a larger slower powder charge. Context always matters.

Great feedback!! This is the king of information I was hoping for by asking the question.

-- Semper Fi --

 

[GunnyUSMC]

Similar here. For a very long time (too long) I avoided messing with inside neck lube like the plague. Same with brushing case necks Too messy, too slow, yada yada.

The thing is... they work. The condition of the neck ID has a lot more effect on consistency of seating than neck tension, up to a point. With smoother necks, you can work with higher neck tensions - or not - without adversely affecting your bullet seating.

As mentioned before, the bullets will tell you what works best in your gun. But being able to seat the bullets more smoothly may change how your accuracy responds to higher neck tension - or not. Try it and find out.

I too went back and forth between neck lube and no neck lube. I settled on dry neck lube but didnt consider increasing my neck tension.

Now i have some more load development to do and that means more range time... YAY!!!

 

[bax]

I would never tell you that low "neck tension" isn't correct for your "hot loads"...

I never thought about it that way. Thanks for the information! I tumble and use graphite dust on necks and that makes seating force more uniform. I will try using a smaller-diameter neck expanding mandrel.

 

[4O6shootist]

I typically aim for 003 tension on 22-7mm, this coukd be 0025, or 0035, but generally 003, 30 cal I test 003 or 004. One will show better one paper right away. I've found 338s(lapua and rum) to like 001-0015, and I figure this is due to the much greater surface area and diameter creating the tension. I generally anneal, and size with a bushing FL die. I do not use a mandrel as it work hardens by working the brass. I've got a hundred freakin bushings. But I can choose the one that gives me what I'm after. I then tumble after trim in walnut/corncob, leaving the dusty residue and carbon inside the necks. Leads to very smooth seating forces. I typically do not neck turn, but have for a few batches of brass, as it was necessary for proper chamber clearance, the turned cases yielded the most consistency. I've found alpha lapua and adg to generally have a thick side and a thin, usually varying 0005-001.