Introducing Runout During Sizing

[Reid]

New member here! Have a (precision) reloading question.

In preparation for neck turning, I'm FL sizing my brass (7RM, Nosler) so the necks don't fit too loosely on the turning mandrel. Die is a Forster FL sizer, press is a Forster co-ax. This brass has been fired a couple of times, but up to now, I've only been resizing using a Lee collet die.

I've been measuring runout on a Forster gauge, right behind the shoulder. Runout is between zero and three ten thousandths (0.0000-0.0003") prior to sizing. After sizing, I'm getting about seven to nine ten thousandths (0.0007-0.0009"). I'm using Imperial wax on the outside of the case up to the shoulder, and Imperial dry lube on the inside of the neck. For a couple of cases, I also tried Imperial wax on the inside of the neck to see if it made a difference, but most are coming out the same.

I realize that my runout is still under 0.001", which might not be anything to worry about, but I hate to add any runout to what are mostly zero-runout brass. I'm wondering if this is normal, and whether there's anything I can do to avoid it.

Any help appreciated!

 

[Lapua40X]

Welcome aboard, Reid. IMO, the Forster FL sizing die places the expander ball higher in the die assembly than others, in order to provide the case with greater support - contributing to greater accuracy in centering the expander ball. But, IMO, it's still not installed with tolerances to maintain the level of runout most of us are looking for. I always remove the expander ball from FL sizing dies that have them and use a bushing style neck sizing die. For the finishing touch I rely on an expander die/mandrel

 

[Reid]

Hi George! Thank you. I have a K&M expander die, as well as a Redding Type-S FL Sizer (both of which I was planning on using later in the brass prep process, after neck turning).

Given my current goal of getting the neck sized down far enough to have a tight fit on the turning pilot (while still fitting, of course) so that I get accurate results from the neck turning op, it sounds like the implicit point in your recommendation is to use a bushing that will bring the ID of my neck to just slightly over the diameter of my pilot (maybe a hair more since, pre-turn, there will be some slight variations in the neck thickness which I will have to accommodate).

Have I got that right?

 

[bobinpa]

In my opinion, you should size the necks down a little too small using a bushing die, then expand them back up using an expander mandrel that is matched to your turning mandrel. FL sizing to the exact size needed to fit the turning mandrel will be difficult at best. I always use Sinclair expanding and turning mandrels. That way the correct clearance is "built in" to the system.

 

[dkhunt14]

I prefer to turn necks before they are really fired. I feel it does a better job and is easier to get them right. Matt

 

[Lapua40X]

...

Have I got that right?

Yeah, that sounds workable to me. I try not to work the brass any more than necessary when sizing so I select the bushing that gets me where I need to be for the next step in whatever process I'm engaged in - turning, bullet seating, etc..

 

[msinc]

Could you clarify exactly where "behind the shoulder" is??? It sounds like you mean just below the junction of the side of the case and the angle of the shoulder if the case was standing vertical as it would in the press???? Or do you mean on the neck just above the angle of the shoulder if the case is standing vertical???
It matters because if it is the first one above, on the side of the case, then you have to have a bad die. If it is on the neck where you are checking it could be the die or the expander not centered properly in the die. Remove the expander, size a case and see if the runout goes away. It is rare to have a die installing runout on cases. It is very common to have the expander itself out of whack.

 

[butchlambert]

New member here! Have a (precision) reloading question.

In preparation for neck turning, I'm FL sizing my brass (7RM, Nosler) so the necks don't fit too loosely on the turning mandrel. Die is a Forster FL sizer, press is a Forster co-ax. This brass has been fired a couple of times, but up to now, I've only been resizing using a Lee collet die.

I've been measuring runout on a Forster gauge, right behind the shoulder. Runout is between zero and three ten thousandths (0.0000-0.0003") prior to sizing. After sizing, I'm getting about seven to nine ten thousandths (0.0007-0.0009"). I'm using Imperial wax on the outside of the case up to the shoulder, and Imperial dry lube on the inside of the neck. For a couple of cases, I also tried Imperial wax on the inside of the neck to see if it made a difference, but most are coming out the same.

I realize that my runout is still under 0.001", which might not be anything to worry about, but I hate to add any runout to what are mostly zero-runout brass. I'm wondering if this is normal, and whether there's anything I can do to avoid it.

Any help appreciated!

You're wasting your time! Get some good windflags and good shooting time and it will help more.

 

[Reid]

Could you clarify exactly where "behind the shoulder" is??? It sounds like you mean just below the junction of the side of the case and the angle of the shoulder if the case was standing vertical as it would in the press???? Or do you mean on the neck just above the angle of the shoulder if the case is standing vertical???
It matters because if it is the first one above, on the side of the case, then you have to have a bad die. If it is on the neck where you are checking it could be the die or the expander not centered properly in the die. Remove the expander, size a case and see if the runout goes away. It is rare to have a die installing runout on cases. It is very common to have the expander itself out of whack.

On the case body--i.e. between the belt and the shoulder, but very close to the shoulder (~1/32" or so).

 

[Reid]

You're wasting your time! Get some good windflags and good shooting time and it will help more.

I live in Minnesota. Maybe some guys like shooting in the cold weather, but I don't. I'll have to live with indoor pistol and working on upping my reloading game for spring.

 

[smoooth]

We could not ask for better weather to shoot in MN, in January! If this is "climate change", I'm all for it!

You want to use the K&M expand mandrel to uniform the necks prior to turning on your K&M neck turner for a nice slip fit.

 

[snert]

Butch! Way to speak it brother! I understand the OP. He wants to make good reloads. I have concluded that handloading and shooting are connected, but each is its own hobby.

 

[butchlambert]

Butch! Way to speak it brother! I understand the OP. He wants to make good reloads. I have concluded that handloading and shooting are connected, but each is its own hobby.

Hey Buddy buddy,

Butch! Way to speak it brother! I understand the OP. He wants to make good reloads. I have concluded that handloading and shooting are connected, but each is its own hobby.

I don't think anybody has the max of .0009 run out max consistently. What will he gain by turning necks as he has a loose neck?