Neck tension schooling

Silvertip13

Silvertip13

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This is in the precision forum because I would like to tap into the knowledge of the guys that shoot and reload at a high level. I understand inconsistent neck tension issues, but the question is how does 0.001" vs 0.002" vs 0.003" neck tension between the loads make a difference? I don't mean in the same lot of reloads. I am meaning, load 50 with 0.001" and the next 50 with 0.002" and the next 50 with 0.003". I have been told many different theories but short of trying it myself, I am curious what the guru's do and know about it. The rifles that I am working on are consistently under 0.4 moa, not factory rifles or chambers. Thanks as always for your time.
 
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The more precise the rifle, the more usefull NT adjustments as a tuning variable will be, in my experience.
A 2 moa rifle being futile to bother with, as vs. a sub half moa or better, which may respond quite nicely.
Most important, is uniformity of annealing and neck wall thickness before even begining to test for NT preferences.
I find a smooth polished inside neck that doesn't score the bullet shanks to contribute as well.

As to actual tension used, I've settled on 2 thou., +/- 1/2 thou. for a field carried PR, as the best balance between max. accuracy, consistency of results, and mechanical integrity of the cartridge to recoil stresses in the mag and real world handling reliability out there.
Have had a few chambers that shot their best with next to no NT whatsoever, but creeping seating depths and spilled powder in the action gets tedious in a hurry out there in a snowdrift.
 
I'm not an expert, but I believe neck tension affects pressure curve and that may affect rifle tune and ES (because of different pressure curve)which in turn may affect accuracy of your rifle. Of course all that depends on powder used, cartridge, chamber design and lot more. So experiment is the only way to find out what your setup will do with different neck tension.
 
vviking said:
I find a smooth polished inside neck that doesn't score the bullet shanks to contribute as well.
Click to expand...

How do you polish the inside of the neck? I've used wire brushes but they get trashed after a few casings, plus they didn't seem to do much good.

I'm at the stage where neck tension, neck turning, annealing, etc are next up in my reloading process. So any good info is always great to hear!
 
How about wrapping some 000 steel wool around a smaller diameter neck brush. Push, twist, pull, then, as you proceed through your cases, you can simply replace the wool with new stuff.
 
Not to sidetrack your thread OP, but as I see it, all the discussion so far is part and parcel to the successfullness of varying the NT, as vs. accuracy question.
frank223:
I wrap 0000 steel wool around an old bore brush then chuck it in the drill/driver. Every 10-15 cases or so will need another small hank of SW added to keep it snug inside the neck/case mouth. Bit of a pita?, yes, but it's worth it. Pull a seated bullet to see the difference a burnished neck interior makes to the bullet's shank as vs. a dirty rough neck.

All stages of neck prep and sizing are indeed important to consistent repeatable results on target, and as for me, .. expecting 1/2 moa or better every single time, .. the priorities are ... (in order of personal perceived importance, and assuming that all cases are to proper trim length and de-burred with a 14 degree tapered inside neck reamer)

- Annealing. Using collet or bushing neck dies that work the brass minimally helps a lot on this, I re-anneal every 3-4 firings.
- Neck interior prep. Smooth. As with annealing, the feel of the press handle while seating will tell all you need to know. Consistent is the goal.
- Outside turn: I used to fussy over this, until going to Lapua brass, now I no longer bother.

Half the fun is in the experimentation OP, .. at the moment I'm into early days of Garand, and 3 thou. + and a firm crimp is looking more and more like the way to go !. lol

:cheers: y'all

Edit: big boar nipped me to the post ... one finger 'ol fart that I am , lol!.
 
M
Silvertip13 said:
This is in the precision forum because I would like to tap into the knowledge of the guys that shoot and reload at a high level. I understand inconsistent neck tension issues, but the question is how does 0.001" vs 0.002" vs 0.003" neck tension between the loads make a difference? I don't mean in the same lot of reloads. I am meaning, load 50 with 0.001" and the next 50 with 0.002" and the next 50 with 0.003". I have been told many different theories but short of trying it myself, I am curious what the guru's do and know about it. The rifles that I am working on are consistently under 0.4 moa, not factory rifles or chambers. Thanks as always for your time.
Click to expand...

If your consistently at .4 Moa , your already as good as most f class and long range rifles shoot.
 
Pesky ab said:
M

If your consistently at .4 Moa , your already as good as most f class and long range rifles shoot.
Click to expand...
There is always room for improvement, and I now the rifles is better then 0.4 moa.
I have been running 0.001" +/- 0.0005 neck tension on reloads, and 0.002" +/- 0.0005" on new Lapua brass. Between the two I can't see any difference on the group sizes, even out to 600 yards. I picked up a new neck die but the bushing with it is giving me 0.003" +/- 0.0005" neck tension. So what is the right amount, or does it not really matter with some rifles?
 
That extra thou. tension from your new neck die?.
Only your rifle knows if it's welcome in your brass, or not.

There seems to be a likelyhood inherent to higher precision rifles prefering lighter NT's, but this not carved into stone either.
 
If you have rifles and the ability to shoot say 1/3 min at LR, then small changes like neck tension will show up.

As a rule of thumb, you want the lowest neck tension that fits how the ammo will be set up and used in the rifle... didn't say nothing, just what is appropriate.

Most F class shooters use 1 to 1.5 thou on prepped and annealed necks... but we single feed and baby our ammo.

The higher the neck tension, the higher the chance to induce runout during seating.. why we avoid adding anymore then absolutely necessary.

Things to watch - Neck thickness (anneal regularly, turn EVERY firing), powder charge, components and mirage/wind.

Good luck...

Jerry
 
General wisdom is 1 thou tension for the brass spring back, 1 thou for tension, then another thou for coated bullets. I have found that up to 5 thou total tension on moly bullets actually improved the group.
 
Mystic Precision said:
.

The higher the neck tension, the higher the chance to induce runout during seating.. why we avoid adding anymore then absolutely necessary.



Good luck...

Jerry
Click to expand...

Jerry,
To what standards do you hold your TIR's for F class comp., measured at the shank to ogive intersection?.

My die rig holds 1.5 thou TIR at worst, most of 'em come in at half a thou. or less, measured at that point.
Considering all the other variables(most notably my really chitty wind calls, lol!) ...

A long winded way of asking ... is it even worth working further on lessening TIR's for this 1/2 moa at best capable casual LR shooter?.

A stupid question I know, it's plain to see that reading mirage better is the way to progress.
 
I keep my runout of the ammo to max 3 thou... put the higher ones, if any as sighters.

Well, was mucking with stuff just to see what would happen... ooops, up to 6 thou runout. Oh well, set them aside for foulers.

Go out and for S&G launch these "high" runout bullets. Shoot the smallest group of the day at 960yds. Sooooo....

I still bring 3 thou or less to a match but if they get rattled in the box, I don't sweat it anymore.

runout... well, maybe it even helps :)

Jerry
 
If neck tension is uniform it doesn't matter more or less. Have a KM arbor press with seating force indication, but using it in its range of operation is difficult. Plans are to install a small hydraulic fixture to pressure gauge and use that to achieve consistent bullet seating tension. Case prep is important for uniform neck tension, chamfers cut in a Wilson trimmer help. The goal is uniform cartridges. Uniformity to last .001".
 
I'm very excited about my L.E WILSON neck die and vld bullet seater! Anyone use these in .338LM before? Supposed to give near perfect zero runout.
 
Runout is not as big of an issue as most people think. As Experts like Jerry mentioned^^^ upto 3 thou runout, I highly doubt that you'll notice any difference on paper, unless of course you shoot rail gun in a tunnel at 500+ meters
 
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