Do or do not? Case mouth expanding?


January 28, 2003, 02:58 PM
I've been reading the ABC's of Reloading and am a little bit confused about the case mouth expanding step. It says that it is normally only done when loading cast bullets, so that the bullet is not shaved as it is loaded into the case. But then in the step by step guide with a jacketed bullet, it still does the expanding.

So am I supposed to use the expanding die for all bullets? Or just cast bullets?

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January 28, 2003, 03:05 PM
Use it all of the time unless you're loading bench rest ammo with special benchrest neck sizing dies. Just make sure that your seating and/or crimping die removes all of the belling.

January 28, 2003, 05:25 PM
I bell the case mouth for all my pistol reloads,i find i can use a little less with jacketed bullets compared to cast.

Mal H
January 28, 2003, 07:57 PM
Same here. I bell all handgun cases so the bullet, lead or jacketed, just barely sits inside the case instead of on top of it. More belling than that isn't necessary and only works the case mouth unnecessarily.

Jim Watson
January 28, 2003, 08:07 PM

What caliber?
In general:

Pistol, expand and flare until the bullet is EASY to start. You will likely lose a pistol case before you wear it out.

Rifle, conventional 2-die sets have the expander ball on the decapping rod. That and a bevel inside the neck are adequate for jacketed bullets. But if you want to do it nice, look at a Lyman M die. It expands and enlarges a bit of the mouth to just over bullet diameter without flaring it. Adds a step, though.
Serious target shooters use bushing dies that size the neck just right so no expander is needed.

January 28, 2003, 10:43 PM
Since I have shaved the bullets in the seating step.

Jacketed pistol bullets get flared just as much, but that's just because I'm too lazy to set the powder/flare die in my Dillon to a different setting.

For rifle cases, I don't flare or bell, I just chamfer the mouths. Save for one - my .45-70.

January 29, 2003, 05:49 AM
I also flare all straight pistol cases regardless of bullet type. It makes things go smoother on a progressive, you're not fumbling around trying to line the bullet up before the press is cycled.
As Gewehr98 said, no need on most rifle cases, just chamfer after trimming.

January 29, 2003, 07:28 AM
I bell for everything, pistol and rifle, lead and jacketed, just enough so the bullet will start in cleanly.

I also expand the necks on rifle brass completely with a Lyman expander die. I ground down the expander ball on the decapper so it doesn't touch the inside of the case mouth. [Zediker is of the general opinion that case stretching occurs when a dual-purpose decapper die is pulled back out through the case neck. My groups and fired case sizes tend to back his theory.] ). Check that the expanding and belling/flaring process is adequate on a rifle round by pulling a bullet and inspecting it. The copper jacket shouldn't be marred. If the brass is chamfered and expanded (etc.) at the correct dimensions, the bullet still looks pristine. The competition seater removes the belling. There's a fine line to be toe'd; just enough expansion to allow for smooth seating, and not so much that recoil seats the bullet any farther into the case.

January 29, 2003, 09:16 AM
Sounds good, I figured it would be best to open it up to seat the bullet easier. Now I know why a turret press would be much faster than a regular single press. I thought two single presses would be good enough! :)

January 30, 2003, 10:54 AM
Belling and expanding are two different things.
Belling is just that..makiing a bell-shaped outward curve in the case neck.Generally used with lead bullets as mentioned.
Expanding is a straight- up-and-down process,or very nearly so.I also think that expanding after sizing causes stretch,requiring trimming.It's kinda like seating and crimping lead bullets in one can do it but two dies is better.

January 30, 2003, 11:06 AM
Good definition SASS. First slightly chamfer the inside of the neck. Then bell only as much as necessary since excess will just shorten case life. EXpander die choice is important to give just enough grip to prevent bullet setback when chambering ( setback raises pressures ! )

January 30, 2003, 11:20 AM
I shoulda made myself clear. I bell all my pistol cases with whatever die is supplied for that caliber set.

I expand my rifle cases with a Lyman expander; it has a very slight tendency to 'bell' the mouth (at least I think so, because it feels wider there) which I remove with the seater die.

I use an RCBS X-die, and so far it has lived up to advertising; my cases (.308 Win) stopped stretching at 2.008" and they're on their 7th firing out of an M1A. The web shows no signs of seperating either, when subjected to the 'paper clip' test. Before the X-die, I'd find cases ready to separate after 3rd or certainly by the 4th firing.

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