Expander ball - to use or not to use

[Cort]

I am the new, proud owner of a custom 6 br. I bought the Redding bushing dies. Do I leave the expander ball in or do I take it out? It seems like sizing the neck with the appropriate bushing that I would not need or want the expander ball.

Thanks,

Cort

 

[Greg110]

Cort, you are correct. If you are going to bushing size, you would NOT use the expander ball, just the decap pin.

 

[RonAKA]

I asked a similar question a while back, when I got my new 6BR. See link here:

http://www.accurateshooter.com/forum/index.php/topic,3750419.0.html

I actually am still using the expander ball as it is very slightly larger than my sized necks. Have not checked lately how much it may be opening up the neck, but earlier I had estimated it to be 0.0003".

The concern about the ball is that it can cause concentricity issues. I use a Forster bushing die, and Forster unlike Redding and others locates their expander ball right up near the neck sizing bushing. Their thought is that this ensures it will be concentric with the neck. For that reason I think there may be some neck tension uniformity advantages.

I believe Redding and RCBS locate the ball much lower down, so possibly could be more of an issue in causing eccentricity.

 

[BoydAllen]

Many shooters have an oversimplified view of expander balls. (expander ball bad...ugh )This is because they do not know how they cause runout.

On a typical one piece die, the part that sizes the neck is so small that when the expander is pulled through the neck, the amount of pull on the case causes it to stretch, just a little, where the neck joins the shoulder, and because of variations in brass thickness and hardness, it will give more on one side than another. This asymmetrical yielding causes the neck to be cocked relative to the case body.

With a bushing die (or a custom one piece die), the diameter of the bushing (or neck ID)can be selected so that only a little expanding is done, which in the case of unturned necks, or turned necks that have been slightly damaged by during ejection, can be an advantage. making the inside of the neck rounder, and more uniform in diameter. With this small amount of expanding the amount of pull on the shoulder is insufficient to cause stretching, so necks are not cocked.

This is not directly on topic, but does illustrate how little things can affect accuracy. If one of my 6PPC cases' necks (turned to less than .009) is bent by my letting it hit a hard floor, simply straightening out the ding and resizing the case does not fix the problem. Even though the neck may look just fine, it will not group with the rest until it has been fired and resized.

 

[Laurie]

With a bushing die (or a custom one piece die), the diameter of the bushing (or neck ID)can be selected so that only a little expanding is done, which in the case of unturned necks, or turned necks that have been slightly damaged by during ejection, can be an advantage. making the inside of the neck rounder, and more uniform in diameter. With this small amount of expanding the amount of pull on the shoulder is insufficient to cause stretching, so necks are not cocked.

+ 1 on Boyd's comments here. You want the ball to just kiss the brass barely touching it. If you lube the inside of the neck too, there is hardly any pressure applied to it.

Using a bushing or custom die without any subsequent neck-expansion needs very consistent brass in terms of neck-wall thickness, ideally neck-turned. If there is any variation, sizing the outside of the neck alone transfers any out of roundness caused by neck-wall variations from the outside of the neck to the inside, so your bullet then has to swage the neck out slightly during seating which has the effect of cocking it, and maybe the neck too, slightly ...... which takes us back to where we were before!

Another answer that I like is to take the expander ball off the decap stem and expand necks after sizing as a separate step using a mandrel expander which does its work on insertion instead of withdrawal and imparts a lot less stress on the neck. You have the choice of the Lyman 'M' die, or if you're considering neck-turning anyway, the Sinclair, K&M or whoever's expander die body with appropriate calibre 'E' (expander) mandrel inserted (remembering that if/when you get around to turning, you want to buy all the bits from the one maker so the 'E' and 'T' mandrels match for easy and accurate turning). You still need to lube the inside neck walls - a cotton bud and Imperial wax is excellent, but remember to remove it with a clean bud after sizing or the remaining lube picks up powder kernels and possibly contaminates them.

 

[RonAKA]

Also remember that all expander balls are not the same size. On my sporting cartridge where I want a tighter fit of the bullet, the ball is a full 0.002" under the size of the bullet. On my 6BR the ball is only 0.0007" under bullet size. Suspect if you were to use a sporting sized ball on a correctly bushing sized neck, it would not even touch.

 

[bozo699]

Cort,
+1 on BoydAllen and Laurie's posts I would like to add one more thing to them.
Somtimes when I am having trouble with concetricity and I have tried everything I can I somtimes loosen up the whole rod assembly so it floats in the die and more often than not it helps.
Wayne.

 

[jo191145]

Good point Wayne

On any die that I use that still has an expander ball I put a rubber O-ring under the decapping assembly lock nut. Screw it hand tight. This allows the expander to "float" and should help lessen runout.
In this scenario the expander being low in the die is more helpful than up high.

 

[bigedp51]

If you have a bur, a ding or raised spot on the inside of your rim the shell holder will cock the case to the side and expander ball will pull the neck off center.

If the decapping assembly is locked down off center it will pull the neck off center.

Engineering principle KISS (keep it simple stupid)

If the expander button in not in the die it cant pull your necks off center.

"Everything should be made as simple as possible, but no simpler."

Albert Einstein

(and that is why the Lee loader is so simple and doesn't have an expander button) :

 

[memilanuk]

With a bushing die (or a custom one piece die), the diameter of the bushing (or neck ID)can be selected so that only a little expanding is done, which in the case of unturned necks, or turned necks that have been slightly damaged by during ejection, can be an advantage. making the inside of the neck rounder, and more uniform in diameter. With this small amount of expanding the amount of pull on the shoulder is insufficient to cause stretching, so necks are not cocked.

+ 1 on Boyd's comments here. You want the ball to just kiss the brass barely touching it. If you lube the inside of the neck too, there is hardly any pressure applied to it.

Been saying this for years...

Ditch the regular expander ball and get Redding's floating carbide expander ball and you can skip all the messing around with o-rings on the stem and whatnot. The carbide ball has a (much) shorter bearing surface so it doesn't drag as much, it's much harder/smoother... so it doesn't drag as much, and it floats on the stem so it self-centers as it comes out the neck. About the only plus to the regular expander ball is that some people claim to polish it down for a custom size - rather hard to do with the tiny carbide ball - but doing that and keeping it concentric starts beggaring belief...

 

[fdshuster]

I also believe in and use the carbide expander ball for factory chambered rounds, like the 223 for use in my AR's. Unlike the claim that no inside lube is required, I do use Imperial Die Size Wax and when checking neck runout before and after, find very little , if any, additional runout, with high quality brass. Never use an expander with any cartridge that I'm loading using the Redding Type S neck bushing dies.

 

[hogan]

I use type S FL sizer dies exclusively.

Helps to chuck the new expander ball in drill chuck and work the ball with crocus cloth to polish and also reduce OD a bit. Polish with Flitz or similar when done. Measure to correspond with your neck bushing goals if you want to be really meticulous.

Hey Redding/Forster! Why not sell OD specific expander balls???

As to the depriming rod itself, adjust length so it knocks primer from case, but just barely. You want to leave the rod loose and then tighten it firmly (having already firmly set length) while rod is still seated in primer pocket. This centers your deprime rod & expander so expander is oriented with case neck and traverses neck squared to the bore.

 

[RonAKA]

Hey Redding/Forster! Why not sell OD specific expander balls???

Forster does sell them. See this link. I had one special ordered.

http://www.forsterproducts.com/categoryShopping.asp?category=22705&catid=19938

 

[Yellow11]

I took delivery of another new rifle yesterday, a 7/300 wsm.

So yesterday evening found me resizing Norma 300 wsm brasses to a 7mm neck, using Redding dies - a make of dies I had never tried before.

My overall plan was to use the Redding custom 7/300 wsm FL resizing die, but without the ball. Use an expander mandrel, neck turning the brass and then after fire forming, re-load using Wilson dies and an arbour press.

What transpired, when I started resizing, I had not experienced before with my other wildcats. Resizing the brass without the ball left the mount of the neck extremely bell mouthed and the use of the mandrel had a tendency to depress the shoulder.

Refitting the ball removed the problem of the bell mouthing, though a generous amount of lubrication was required inside the neck to make the whole process flow without too much grunt.

Not too sure how I am going to proceed from here, other than perhaps use an alternative die make. It may well be that I'll get a 300 wsm mandrel and turn the neck down a touch before resizing and then turning the neck again.

Any helpful observations...

 

[BoydAllen]

You might consider expanding and turning the brass without FL sizing. The issue is the ID of the neck of the die. All one piece dies (unless custom ordered) have undersized neck IDs and depend on the expander ball to get the neck up to where it should be. If you want a one piece die with a custom neck ID, I understand that Forster will hone out one of their dies for a small fee. The bell at the end of the neck is more about the condition of the brass than the die.

 

[Yellow11]

... but it is supposed to be a custom die and I am trying to reduce the 300 wsm neck to 7mm.

That said, I'll give Fosters a call.

 

[bozo699]

Hey Redding/Forster! Why not sell OD specific expander balls???

Forster does sell them. See this link. I had one special ordered.

http://www.forsterproducts.com/categoryShopping.asp?category=22705&catid=19938

RonAKA,
I swear you have a link for anything mentioned ;D Thats a good thing,Thanks.
Wayne.