Neck tension and cast bullets

[Wolfdog91]

Anyone happen to mess with neck tension setting with it come to rifle cast ?

[brokeasajoke]

While I don't have anything to offer I'm curious if you are going to use a bushing die or a Lee neck die and polish the mandrel down.

[gwpercle]

I do it in a simple way ... Lets take 30-06 as an example .
My standard Redding dies have a .308" neck expander and leave it so expanded for .308" dia. jacketed bullets ... I cast my 30-06 boolits in a mould that drops them .309" and run them through a .309" sizer die to round up and lube .
The Neck Tension is about perfect ... To help seating I use a Lymn M-Die or NOE neck flare / expanding insert tool to put a two step flare so the base doen't get shaved or deformed during boolit seating .

If I need / want tighter neck tension ... I simply use a .310" dia. boolit ... or a coated boolit .
You don't really need that much neck tension ... just enough to hold the boolit securely and that's all you need .

I don't have any specific "setting" ...I'm just an old school , simple reloader trying to get by The Easy Way .
Gary

[charlie b]

I just use the Lee collet neck sizer. Flare just the case mouth (no M die). Size bullets to .310. Lee collet crimp such that the flare is gone. If I am working with clean cases then I will make sure there is some case lube inside the neck when seating.

This gives me a consistent tension. Haven't felt the need to change it.

I have tried various amounts of crimp. For me no crimp is best.

[Rapier]

If you have read any Pope writing ou would see that his method was to pull the bullet out about 1/4" by his fingers the seat the bullet with the bolt closure. I do not usually crimp bullets in a rifle at all, especially cast. I do have expanders for different cast bullets in rifle cases so they do not scrape the bearing surface past my sizing.

[megasupermagnum]

Yes. Somewhere around .004" to .005" you might start to see them sizing down your bullets. .001" is pretty light, but ok in some rifles. I like as little as needed, usually in that .001" to .002" range. A semi auto, I wouldn't consider less than .002".

[stubshaft]

I go the other way and use different size NOE neck expanders to get the tension that I want. It always seemed counter-productive that people would cast and size their bullets so carefully then dump them in a tight necked case, where the case would size the bullet down and wonder why accuracy sucked.

[PopcornSutton]

A bushing die is the way to go, with turned necks. With accuracy in mind, you need to control variables. Neck tension, seating depth make a difference. I start with enough tension I can feel a push while seating, and work on the load from there. Once I have the load fairly worked out, neck tension can be tried simply by changing the bushing. Plus, different powders like different tension. Some want a lot of tension, some not so much.

[quack1]

I make my own neck expanders to give me about .002 neck tension on rifle cartridges. I'm a brass scrounger, so I anneal all necks before the first loading and then after every few firings, to keep even tension and prevent any bullet sizing when seating.

[Forrest r]

I have a set of rcbs 308w dies that has the factory/jacketed bullet expander. I called them and asked to buy a 303 british expander for jacketed bullets. They sent me the 303b free (thank you rcbs).

I tested using no expander vs the 308w jacketed expander vs the 303b expander. I only tested 100rounds rounds of each expander using a lee 160gr tl bullet sized to .310". I used mixed nato brass (6/7 different head stamps).

There were a lot less fliers with the 303b expander than with the 308w jacketed bullet expander.

I really couldn't tell the difference between the jacketed expander and using no expander.

[Larry Gibson]

I've found .002" neck tension to give the best accuracy IF the cast bullet quality, the load and the rifle is capable of telling the difference. For most cast bullets w/GCs in most rifles, especially milsurps used with iron sights, neck tension is immaterial to accuracy as long as it runs from .002 upwards of .005. Too much neck tesion can cause damage to the bullet when seating.

[waksupi]

I usually neck size around a third of the neck.

[megasupermagnum]

I usually neck size around a third of the neck.

Why?

[Calamity Jake]

Redding bushing dies set up for .002 neck tenson

[Shopdog]

Pretty broad question?

The cast community is very vast,some folks are happy to just safely get from point A to B. Others choose to dig right much deeper. Some guys just want 2+2=4 type of answer... others don't care about the answer and are only concerned with the processes involved.

.002 is a VERY safe bet. But being as neck "tension" #'s have to be one of the easiest things to test for..... well,why wouldn't you?

Try .002 vs .004 just to see if your rig can flesh the difference. Any closer,saying .0015 vs .002,and the noise from other things involved start to creep in.... annealing for instance,or the process (inside mandrel vs outside bushing). So testing from the extreme ends,headed towards each other "may" be a better approach on this application. Good luck with your shooting.

[Bigslug]

Not so much with that specific intent. Gwpercle's post hits pretty close to my thinking: if, for example, our .45-70 came from the factory set up to take a .458" jacketed bullet to fit that exact groove diameter, most factory dies are set for that, and our cast bullets are in the .459"-.460" range, it's rare that we'll have insufficient grip on the slug. But Calamity Jake is also right - the bushing dies are there when you need them and are useful for assorted rabbit holes. Mostly, I'm after reliable function, so "neck tension" is going to consist of ensuring the bullet isn't so loose as to get set back, and also taking the flare out of the case mouth so the round doesn't snag while trying to chamber.

This was more of a jacketed bullet observation - I did note that a particular 5.56 bullet/powder combination delivered tighter velocity spreads over the chronograph when the bullets were crimped in the cannelure - presumably from a more consistent start of the burn with the bullet corked in the case and the powder held in place fractionally longer. Unfortunately, this was near the time when my dad and I were starting to move away from moly coating, so I can't recall if that load had those lubed properties or not. At any rate, my guess is that the larger diameter and swaging down of a cast bullet would tend to have a similar delaying effect regardless of what was going on in the case neck.

[waksupi]

Why?

Just to hold the bullet in place. I find I get best accuracy this way too, probably because the lower part of the neck aligns the cartridge with the throat a bit better. That's just a guess, but as long as I believe it, it works for me!

[charlie b]

Just something to think about.

If someone is shooting consistently less than MOA at ranges beyond 200yd then I'd follow their advice.

I am not quite there yet. Less than MOA quite a bit, but, mine are really in the 1.5 MOA range out at 500yd.

[higgins]

The expanding balls I use for .30/30, .30/06, and .308 win. are .001-.002 smaller than bullet diameter. Just enough to hold the bullet snugly so it doesn't come out of place in handling. It's not critical in my case because I single-load the rounds. I also use a Lee factory crimp die to remove the flare and apply a light crimp. If I were feeding the rounds from the magazine I'd probably use not less than .002 smaller.

[gloob]

I use oversize expanders in all my calibers I load cast bullets, and I have a pretty strong opinion on this that doesn't seem to be very popular.

A lot of people assume your expander has to be 1-2 thous smaller than the bullet to get good neck tension. This is easily observed to be false, IME.

If neck sizing, you generally get full neck tension when your mandrel is 2 thous (or more) smaller than the bullet. That's because the neck isn't sized, and it springs back out, a little more than 1 thou. That leaves the neck slightly smaller than the bullet, by up to maybe 1 thous or less, which is little enough difference that the brass can elastically stretch to accommodate the bullet, providing proper neck tension without making the seating any more difficult (in regards to concentricity of seating or in some cartridges you can even get case swaging of the base of your bullets).

When you're taking an adequately (over) sized case and push an expander through it, the brass is also going to spring back as you withdraw the expander. But it's going to spring back smaller. The proper size for an expander plug, imo, is the same diameter as the bullet, plus or minus a thous.

If you pulled bullets from a bunch of cases, could you just seat new bullets in? Yes. Provided they had neck tension to begin with, and you insert the same diameter bullets you just pulled, and provided there was no excessive crimp on the mouths, you could just flare the mouths and reseat bullets with perfectly good neck tension. The brass is elastic and stretches about a thous or so. If the bullet has neck tension, the case will spring back when you pull the bullet, and it will hold a new bullet just fine.


Using a smaller expander, the bullets may get harder to seat. But that doesn't affect neck tension. It just means your bullet is finishing the expanding, itself. Then the neck tension that is left is pretty similar.

[gloob]

If lubed, cast bullets also have less friction to the case compared to jacketed. In cartridges with limited neck to bullet contact, like say 223, this makes the step flare critical. The diameter of the expander plug at the flare has to be at least 2-3 thousandth larger than the diameter of the bullet. If the flare is gradual, like with a universal flaring die, by the time your mouth will stop shaving bullets, it may destroy neck tension in a significant portion of the neck behind the mouth. In such cartridges, a sharp step flare can be important.