my 30-30 case starts out as 2.3 length then I clean the inside of the neck and dust a little graphite on the inside of the neck and lube the case with hornady case lube then size the case it comes out at 2.4. Then when I seat a 100 half jacket plinker bullet there is somewhat detectable bulge denoting the outline of the bullet. It's looks like the neck is sized too small the when the bullet is seated it forces the neck back out. This happens with once fired cases and new remington brass. Are my hornady dies messing me up?

two issues.....
1 length increasing

and
2. the hourglass appearance

It's normal and usual for a case to grow in length in the resizing process.....however there's something wrong here.....you need to measure cases to three places....instead of 2.3 inches you need to state it to 2.305 (or whatever) inches....three places. It's just not in the cards for a caser to grow 0.1 inches....that's almost 1/8" and it don't happen. You need to measure much more precisely....use a precision caliper and measure to three places.

About the hourglass effect. I don't like it either but there's nothing wrong with it. Lots of dies do this and especially with pistol cases. If you was seating longer 170 grain bullets you might not notice it.

IMO just accept it and get on with reloading.

I just tried a remington new brass. measured 2.32 before size and 2.375 after size. Is that about normal?

no...definitely not.....the .30-30 should be 2.039 max.

I'm talking the case only.....are you measuring the loaded case with the bullet in it?

Or are you misreading your measuring instrument.....do you mean 2.032 and 2.0375?

Here's a photo of a calipers set at 2.032

The first tow digits (2.0) are read from the main beam and only the last two digits (32) are read from the dial.

Model20,
You could try measuring your neck expander,mine is 0.3066 ie nearly .307,(for a .308 projectile.)

And you could try measuring your projectiles.
When I'm loading larger dia lead bullets I use a .303 size expander (made for .311 size bullets.)

On full length sizing my cases may stretch something like 0.008" (8 thou.)
If all else fails, summons up HotCore.

John L>

Oops.....it's 2.032 and 2.0375. is that an acceptable stretch?
Also I measured the bullet it's .308 and the expander is slightly less that .308

your growth is about .005 and that's normal and acceptable....it's also under the 2.039 mentioned earlier. Now, if the powder is the right stuff and right amount the loads you made should be ready to shoot. Have at it!!!!!