Home Forums Reloading Big Game Rifles Sinclair Expander die or the like

Anyone else notice your case length shortens just a bit after expanding the neck with an expander die such as the Sinclair? My 06 brass shortens about 5-6 thousandths from the full length sizing to finishing with the neck expander die. Just wondering how common this is with others. Thanks for any feedback. Not sure if it has any practical impact.

I read your comment and then went and expanded necks on .270 Win brass and .308 brass with a Sinclair expander mandrel. I measured each before and after and no shrinkage or growth of any type. Sounds like you are screwing the mandrel die in too much.

👍🏼 That may also explain why the runout was so bad (.005) with my neck expanded brass as well??….

With good brass my expansion mandrel dies do not cause any runout.

Do you lube the inside of the necks?

I lightly graphite necks and the top half the shoulders with Reddings imperial graphite applicator beads. Then I lube the case body, then full length size w/o expander, then run a carbide expander mandrel. Brass is annealed after every firing.

Yes, I use Imperial dry lube

Rather...
When you run you cases into the Sinclair expander, do you run them in all the way until they bottom out and the case mouth bumps the shoulder on the expander mandrel? If so, this is likely the source of the bump back.
I only run my cases over the mandrel until it goes all the way into the neck, and don't let it bottom out.
Even then I will see the brass come of the expander a thousandth or so shorter than before the pass, but never anything like you describe.
And rather than induce any runout, I sometimes see the sized brass have a little LESS runout after the pass over the expander mandrel.

Hope any of this helps.

Rex

Here’s my latest observation. I was running my expander mandrels through necks that had not been lubed, and had been full length sized in my standard dies, with no expander ball in the dies. This made for quite narrow necks. The expander mandrel would then open up the necks considerably, inducing run out and shortening the case a few thousandths.
I removed my depriming pin in the dies, raised the expander balls to almost touching the neck when the case is fully pressed into the die. This keeps the neck aligned in the die as the expander ball stretches the neck back out. Minimal run out. Then I run the expander mandrel through the neck to uniform neck tension. Much less run out for me with this technique and hardly no case shortening. Also less force needed to expand the necks this way rather than full length resizing with no expander ball. I also deprime with a universal depriming die.

If you ended up using the expander ball then why do the necks need further uniforming with the expander mandrel?

Why were you pushing the expander mandrel into unlubed necks?

When I got this Wilson bushing die first thing I noticed was no expander button on the decapping rod....I thought I might need another step or die so I called Wilson.

They told me using their newer neck bushing dies (with the proper neck sizing bushing) that "only new cases" need to be run over a neck expander.

[quote=mathman]If you ended up using the expander ball then why do the necks need further uniforming with the expander mandrel?

Why were you pushing the expander mandrel into unlubed necks?[/

Just didn’t think I wanted to mess with cleaning the lubed, inside case necks.

Depends on the lube you use but for bigger calibers (mostly .358 and up which have a lot of bullet/brass contact relative to smaller calibers) I intentionally leave both one shot and graphite lube on the inside of the necks. Otherwise with virgin and even once fired brass I get crazy runout due to bullet seating friction, even at low neck tensions and with perfect chamfers. I've shot these lubed-neck rounds vs unlubed neck rounds and even at 750 yards they shoot into the same group.

Point being: you can leave certain lubes on the inside of your necks: all the graphite lubes and also one shot.

Though it sounds like you've already solved the problem.

I use the Imperial dry lube and have no worries about removing it. If I feel really picky a quick swipe with a nylon brush does the trick.

I’ll have to check that out. Do you need some kind of steel balls to mix it in with to apply it or just dip it in a pile of powder?

There are little ceramic beads in a jar. Their surface texture carries the powdered lube. You get a jar of the straight powder to charge/recharge the beads.



The beads look darker than in the pic when I consider them sufficiently charged. You don't have to load a bunch of the powder in there, but you'll need to give the beads a good bit of shaking to get the initial coating to take.

Thanks for the heads up. Just ordered it.

I can save you a step. Makes a difference if you’re doing mass quantities of brass. Instead of using a universal depriming die, and I have one, just use an expander ball a caliber less than your cartridge case. That way you can deprime a case as you size it without expanding the neck with a “pull thru”. Keeping an expander ball installed allows the decapping pin to stay on board. As an example I have used a .17 cal expander with .223 / 5.56 brass and a .264 expander with .270 Win brass. Then exchange the undersized expander for the correct one to “push size” the case neck. For 5.56 I just replaced the expander ball with the .17 ball and use a separate die with a .224 ball for push sizing. YMMV

Where'd you find it? Everywhere I checked was sold out.
Thanks,
Rex