Confused or just up to late - Neck Tension

CoronaCA

Beginner
Oct 18, 2017
11
0
Hey all.

Loading for my son and although I have been reloading for a while I never paid attention to neck tension. Full length size it, Redding standard FL, drop powder and seat the bullet and shoot. But......I have been watching and reading things. That is problem one. So here is my issue and maybe I don't get it.

Loaded round (300WM with 190 ABLR) is .3330. The brass is Winchester 1x nickel plated. Sized case without bullet is .326. Redding FL non-bushing die and I am using a Mitutoyo digital caliper which seems to calibrated (tested with some pins).

So if I understand correctly:

.333 Loaded round LESS .326 sized casing = Neck Tension. So in my case that would be .333-.326 = .007? That seems MUCH higher than .002 that is most recommended? Shouldnt my target be .331 for an unloaded sized case? In other cases with some SSTs I am coming in at .335 so that means I am at .009?

So if this is correct, how do I fix it? What could causing so much NT with factory dies. Or do I not get it at all?

N
 

ElmerThud

Handloader
Jul 16, 2011
769
15
The rabbit hole of reloading goes very deep & can be stupidly expensive.
So, if the ammo you make shoots well enough... why worry?
If you're 'Match shooting' or 'Bench rest shooting' it's a different matter, but for hunting, provided you're happy as things are, simply carry on doing what you're doing.

Personally, I've never measured the ID of my case mouths, but I do use a bronze bore brush to clean out the carbon in there from the fired case.
:grin:
 

jimbires

Handloader
Aug 16, 2011
2,503
475
your math is correct . probably the easiest way to get less neck tension is to use expander mandrels after the brass is full length resized . you can buy sets of these . you will also need a mandrel holding die . I have a few sets from 21 century , I'm sure others make these too .

https://21stcenturyinnovation.com/buy-o ... /v/E28-Kit
https://21stcenturyinnovation.com/buy-o ... 20w%2Fring


neck tension is another rabbit hole to explore to try to up your ammo .
playing with neck tension will affect velocity extreme spreads . it can affect accuracy too . to much tension can deform bullets when seating , distort the ogive , ring the ogive , pinch the hollow point , scuff the bullet shank . not enough tension can allow the bullets to move from powder push ,recoil , and just carrying them . it's another tuning tool that you might not find worth while , for your type of shooting . if you crimp bullets , there is not much sense in playing here , the crimp will override the lighter tension .
 

desertcj

Handloader
Sep 27, 2010
816
57
I own very few full length sizing dies. There are situations where I'd prefer them but for the most part I use Lee collet neck dies in conjunction with Redding body dies although the body die is rarely used. Works for me and I haven't had any problems hunting with neck sized only brass. I have thought about playing with expander mandrel though...
 

Dr. Vette

Handloader
Apr 16, 2012
1,334
65
Your sized case seems tight.

If you have any, try it with a brass case instead of the nickel plated.
Better yet, try it with an annealed brass case.

I suspect you will see different values.
 

jezzolo

Handloader
Nov 14, 2005
306
16
Like the dr. says, try regular brass. That plated stuff will do in a pinch but try to avoid it.
 

grry10

Handloader
Dec 7, 2007
303
71
The easiest way to .002" neck tension is to get a Sinclair expander die and a .306" turning mandrel from Brownell. Your bullet diameter is .308", so running a .306" turning mandrel into your sized case will open it to the desired .306" for .002" of neck tension. I use Sinclair's stainless turning mandrels ($9.99) and the expander die that holds the mandrel is less than $40. The same die will work with .17-.338 caliber mandrels. Hope this helps you.
 

wvbuckbuster

Handloader
Nov 5, 2015
1,507
627
When I was shooting benchrest I tried different bushings for neck tension, and it will make a difference in accuracy. For hunting loads i just full-length size with plenty of accuracy for my deer hunting rifles. Dan.
 

SJB358

Ballistician
Dec 24, 2006
31,398
757
When I was shooting benchrest I tried different bushings for neck tension, and it will make a difference in accuracy. For hunting loads i just full-length size with plenty of accuracy for my deer hunting rifles. Dan.
I’m with Dan. Redding FL bushing dies are awesome.

I use .002 under expander Mandrels where I don’t have bushing dies.
 
Top