How To Ensure Setback, or Beware How Much You Fill Those Cans

[Khornet]

Loading up a bunch of .40 S&W yesterday, using the same gear I've used since '92. I use a single-stage. When all my cases are charged and checked, I 'seat' a bullet in each with a little finger pressure; that way I can pick 'em up and shove in the press without having to pick up two objects. As I was doing this, I found quite a few (32 of 400) in which I could fully seat the bullet with ease. As if they'd not been sized, yet sized they surely had been because they had fresh primers. OD of these loose cases was measurably greater than the normal ones. Checked all my gear--ok. Ran a few of the loose cases through the sizer, and they became tight again. What gives?? All bullets which were loose were fine in other cases and all miked the same.

I have quite a bit of .40 brass, especially since Bravocharlie, who doesn't reload, got a .40. My ammo cans are crammed. Closing an overfull can caused some cases to be deformed enough to fail to grip a bullet. The loosest rounds were noticeably out of round.

I never thought such deformation could happen but there it is. Lesson learned. Don't be cheap--get another can.

 

[bravocharlie]

My guess is that the 32 out of 400 (8%) slipped through your work flow due to the distractions found in your work area:

10 meter pistol range
2 safes
low pipes to clunk your noggin on

and most importantly,

the beer refrigerator.

 

[tex_n_cal]

Interesting...I never had thought about out of round cases being un-salvageable. Soemthing to watch for...

What diameter is the expander plug in your dies? I like to turn mine down to .392 or so, to ensure tight bullet fit in either 10mm or .40.

 

[Dave R]

Yeah, my first thought is you might have over-expanded the cases during that process. Just a thought.

 

[Black Snowman]

Over expanding or old work-hardened brass possibly.

 

[Khornet]

Over expanded? Work hardened?

Nah. As I said, a loose case re-run through the same die will come out fine.

What do you mean by expander plug? I see no such thing in my RCBS carbide die; there is just a carbide ring at the opening and the decapping pin. Not like rifle dies, which do size and then re-expand the neck. I simply see no way I could over-expand even if I tried. Even if there were some sort of expander, the case as it leaves the die will have to go through that carbide sizer ring again.

Likewise, BC, there is only one diameter in the die. It cannot be varied. Run the case fully into the die and it's sized. And with my die setting, the primer doesn't pop out until the ram is at the top. So any case with a new primer has been fully sized.

The loose cases were squashed by being at the top of an over-filled ammo can.

 

[tex_n_cal]

What do you mean by expander plug?

The male thingy in the #2 die, which expands and bells the case mouth, prior to bullet seating.

Most reloading dies Mfrs make these plugs only .001-.002" smaller than bullet diameter. That's not tight enough, according to me, and according to other experts, for revolvers and especially not for autoloaders.

If the bullet has a channellure, a crimp can help prevent bullet setback, as the case mouth will hang up in the groove. The problem is, many aftermarket bullets, especially JHP's for autoloaders, don't have channellures (crimping grooves).

Dave Scovil of Handloader proved that velocity variation and accuracy improved, when BOTH a hard crimp and tight bullet fit were used in a .45 Colt loads. Having a tight bullets is good for revos and a safety concern as well in autoloaders. A tight bullet fit and firm crimp = consistent accuracy, velocity, and no Kb!

 

[Khornet]

Yes, but that affects only the mouth, no? You don't bell more than a tiny bit, or you brass cracks pretty quick. These loose cases would permit me to easily push the bullet all the way in to the bottom. Problem goes away after running them thru the sizer again. Then run them thru the case mouth die and they are still fine.

 

[Khornet]

Ok,

went home and unscrewed the 'expander' button from my #2 die. It has a pilot nearly the diameter of the case interior, ending in a sloping shoulder which does the mouth belling. The pilot portion will slide easily into a sized case, and clearly does nothing at all with respect to the grip on the bullet. The only portion of the case affected by the die is the top fraction of a millimeter, around the mouth, and that gets squeezed back down by the crimp.

So I have to ask: what is all the talk I read here about 'undersized' expander buttons to prevent setback? Can't see how they would make any difference at all. Smaller-diameter sizing die, maybe. Expander? No.

 

[tex_n_cal]

That's really odd. If a brand new .40 bullet will slip into a freshly sized case, then your sizing die may be defective. It does happen - I have seen two sets of defective reloading dies in the past.

The .41 magnum uses a bullet that is .413 dia, as opposed to the .400 dia of the .40/10mm bullets. Perhaps your sizer die was incorrectly made to .41 mag specs?

Start measuring stuff and tell us what dimensions you have - we can check it against our dies.

 

[Khornet]

Tex,

I've loaded plenty before and since with this same die. The loose cases were simply run through the sizer again and they were then fine. The cases were being deformed by the closing of the over-filled ammo can.

 

[tex_n_cal]

well, I've never seen that happen before, where a case has to be sized twice by the same die to make it the right size. Once should be enough, or else prove the case to be unusable.

In any case, an expander plug (or pilot as you call it) needs to be at least .005" smaller than the bullet diameter, to give a good tight bullet fit, in my experience.

 

[John C]

"So I have to ask: what is all the talk I read here about 'undersized' expander buttons to prevent setback? Can't see how they would make any difference at all. Smaller-diameter sizing die, maybe. Expander? No."

The sizer you have is smashing the brass down to the correct size. If the expander button is too large, it is then stretching the case mouths too large, allowing the bullets to slide too far into the case. As others have said, a small expander button allows for tighter bullet seating, independent of the crimp.

-John C

 

[BluesBear]

Get a micromter and chech the inside diameter and outside diameter of your sized cases.

It's possible your resizing die is a little "loose". That is it's not resizing them quite enough.you should not be able to insert a properly sized bullet into a resized case without running it through the expanding/belling die.

If so and it's an RCBS they'll replace it.

 

[Khornet]

Guys,

You're missing something.

You size and bell a case in dies which are correct.

Then you place it on the top of the pile of brass in an over-full GI ammo can.

Then you cam that lid closed.

When you take it out it will be out of round from being squashed between the steel lid and the rest of the brass.

Now when you place a bullet in it, the bullet will slide freely in.

So you take the bullet out, and you examine the case. You see that it has been deformed.

Then you run it through the sizer and belling dies again, and it's fine.

Same as if you sized the case, belled it, and then stepped on it. If the case doesn't then hold the bullet, you don't get out your caliper and mike your dies, you just remember not to step on your sized brass.