Neck tension schooling

All I need to know about run out's potential affect as to the deterioration of LR precision, became obvious with the first few sessions shooting my handloads into sub half moa out to 500, moa'ish to 1000.
That happenened when I finally got real dies and a dial guage to measure.

Less is better.
Fewer uncalled or unexplained "flyers".

As Jerry has opined, there is likely a tipping point of too crooked where things will start to open up as a result. Where exactly that point is ... is a yet another variable.

I can say with certainty from long experience ... freshly annealed and seated dead straight does go a long way to hitting the small gongs way out there, for me at least.

:cheers::wave:
 
Last edited:
WRT to runout, distance actually reduces the affect of runout. With the right amount of twist, a bullet wants to stop wobbling around its axis... as they say, it goes to sleep.

As long as you are not talking wonky cockeyed loading, the largest affect of runout should be visible in the first 300yds. Then, if stability theory is correct, the bullet will self damp and things settle down.

One of the reasons, I feel SR groups can be similar to longer distance groups in actual inches.

The wobble stops, the trajectory straightens out, the bullet follows true to target. Or they stop on a very divergent path and things go very wrong at moderate distances. Testing and tuning will prove what you are working with.

I narrow down my loads at say 300m, launch the best loads out to say 500/600m and see what happens. If all is well, groups at 1000yds should be solid unless you have a true stability issue, crappy bullet design, or can't read the conditions.

Or can't shoot... shhhh, that never happens :)

Test it for yourself and remember, some bullets are fussier about bullet runout then others. Less is always better.. why not, we have the tools and it really isn't any more work to get it right.

Cost the same to make crappy ammo vs good.

But powder charge variance has a profound affect on your groups. As do primers.

Runout, at least a few thou here and there, not so much.

YMMV.

Jerry
 
Mystic Precision said:
Or can't shoot... shhhh, that never happens :)

Test it for yourself and remember, some bullets are fussier about bullet runout then others. Less is always better.. why not, we have the tools and it really isn't any more work to get it right.

Cost the same to make crappy ammo vs good.

But powder charge variance has a profound affect on your groups. As do primers.

Runout, at least a few thou here and there, not so much.

YMMV.

Jerry
Click to expand...

And that needed to get said.

Gotta say Jerry, the knowledge and insight that you've posted here over the years has been a gold mine for guys like me ... thanks!. ... and keep it coming!.
 
calgarycanada said:
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
Click to expand...
Well I shoot a Pgw rifle so ya...it is a railgun.
 
Silvertip13 said:
Thanks Jerry for your input on runout, but how about the original question about neck tension?
Click to expand...

The key is that you use as little as needed to get the job done (load tuning figures this out) but more importantly... maintain the same level of neck tension as the cases age.

Annealing, outside neck turning, proper sizing - proper neck care is what this is all about. Like weighing powder charges, we are looking for the same, same, same.

What it is within reason, is not that important as you will load tune for it. But you must have a process to keep things consistent from firing to firing.

Jerry
 
Precision and accuracy are byproducts of uniformity, and for that reason we make every attempt to minimize tolerances; yet all manufactured products are produced within a specified tolerance range. Thus the amount of neck tension is less important than the consistency of that neck tension. When in doubt, load the bullet to jam length, a bullet that is jammed into the lead mitigates any issues that are related to the inconstancy of neck tension of bullets seated to a jump length. IMHO, loading bullets to a jump length unnecessarily introduces a variable that can otherwise be ignored. The exception to the rule is where rounds must be cycled through a magazine, as this may well require bullets to be seated on the short side. In such circumstances annealing, provides a means of uniforming neck tension, provided the annealing process is uniform, which in of itself presents a challenge. Another part of the challenge is the result of work hardening of the case necks. As case necks work harden, bullet pull weight increases, and pressure and velocity rises. This is the primary reason why sorting brass by the numbering of firings is important, in an attempt to minimize the extreme velocity spread, and uniform the standard deviation. Sizing for optimum bullet pull weight, as we can see, depends on a number of other variables, so I doubt if the actual measurement matters very much, provided that the bullet is held securely enough that it cannot be rotated with the fingers.
 
For op, I suggest that neck tension is less about accuracy and more about brass life. One you've got consistency and uniformity down pat the only difference would be how much the brass has to expand before hitting the chamber wall. This will also depend a lot on your chamber. Lots of bench guys get custom clambering for very thin walled necks. These tight designs mean the brass has very little to give. Just enough to release the bullet. Less neck expansion equals longer lasting brass. Annealing would negate a lot of this.

Long story short, just stick to 1.5 to 2 thou.
 
I tried this a few weeks backs. My test I did with my .308 was FL resize and leave the neck as it came out of the FL die. Then 3 more FL resized and then resized the necks with bushings .334-.336 (redding bushings if you're wondering) and then a last batch of fired cases with the neck tension I had been running previously that had worked as my base line.

I found that FL resized and neck sized to .334 gave me 2, 3 shot, 3/4" groupings at 300yds. The larger bushings gave me about 1 to 1.5in groupings and straight FL gave just under 1.5"

All same brass lot, same bullet lot and powder lot + charge, primers, OAL. It seemed for me that the tighter the squeeze was giving more consistent burn rates and producing the right harmonics.

Short of trying it for your self and seeing, all I can say is that, yes it does work.
 
glockgrouptherapy said:
I tried this a few weeks backs. My test I did with my .308 was FL resize and leave the neck as it came out of the FL die. Then 3 more FL resized and then resized the necks with bushings .334-.336 (redding bushings if you're wondering) and then a last batch of fired cases with the neck tension I had been running previously that had worked as my base line.

I found that FL resized and neck sized to .334 gave me 2, 3 shot, 3/4" groupings at 300yds. The larger bushings gave me about 1 to 1.5in groupings and straight FL gave just under 1.5"

All same brass lot, same bullet lot and powder lot + charge, primers, OAL. It seemed for me that the tighter the squeeze was giving more consistent burn rates and producing the right harmonics.

Short of trying it for your self and seeing, all I can say is that, yes it does work.
Click to expand...

I don't load for 308, what was your neck tension measurements?
 
swissinn said:
Unless you are neck turning and have a tight chamber I think most manufacturers recommend 2-3 thou.
Click to expand...

Most manufactures? Are you talking rifle man's, bullet man's or reloading tool man's?
The chambers I am testing with are tight , and set at no-turn dimensions for a specific type and lot of brass. Just asking about seen differences and results on neck tension changes. Testing out of precision rifles is kind of a given, as the ordinary rifle probably won't benefit from changing neck tension.
 
tourist said:
To answer your specific question, I once loaded 20 rounds of 308, 10 with 3 thou and 10 with 2 thou neck tension. Shot at 100 yds using a chronograph. There was no difference in accuracy but 18 to 20 fps velocity difference with 2 thou being lower. 155 grain bullets and 30 in. barrel.
Click to expand...

Thanks for the reply, what was your extreme spreads? Were they better with one or the other?
 
You must log in or register to reply here.
Back
Top Bottom