Neck expanding GC or PB difference

[Dman75]

Have a question about case neck expanding for bullets with gas check and one without. I wasn’t able to do this apple for apple comparison but…
Just got expanders for my 44mag and 30-30. The 44 I use 240 gr powder coated sized to .433 for my oversized bore Marlin. The 30-30 is 311041 lubed and gc sized to .312 for my micro groove Marlin. The 44 expander is .430 and 30 cal is .310.

Checking the 44 - bullets seated with/without using the expander there is a .004 difference in seated bullet brass. Using the new expander it gives me 1.5/2 thousands chamber clearance. Exactly what I wanted.

Checking the 30-30 - the is no difference in neck size with or without the expander with a bullet seated. The expander definitely expands the neck. Measuring empty brass necks it is expanding about .004. It doesn’t appear that the bullet is getting swaged down like the 44 did without the expander. Is this because of the gas check? Thinking at least it’s going to be more consistent neck tension but interested if anyone else noticed this when using a check or not.

[Winger Ed.]

Expansion is only to get enough clearance of the boolit to go into the case mouth.
After the boolit goes through the sizer-- Gas check or not, they should be the same diameter.

If they chamber up, the crimp is good, and they're safe & accurate--
I wouldn't worry about splitting hairs of .004 or so.

Some of your differences may be in various lots of brass having slight differences in neck wall thickness.
If the wall difference is .002, by the time you measure diameter, you're up to .004.

[centershot]

Whether PB or GC, use a Lyman "M" die to expand the case neck. It has been shown that too much neck tension (too little neck expansion) can cause the lead bullet to be squeezed undersize. This is usually caused by using the standard expander on the reloading die set, which is designed for jacketed bullets, or by applying too much crimp, or both.

[Dman75]

Whether PB or GC, use a Lyman "M" die to expand the case neck. It has been shown that too much neck tension (too little neck expansion) can cause the lead bullet to be squeezed undersize. This is usually caused by using the standard expander on the reloading die set, which is designed for jacketed bullets, or by applying too much crimp, or both.

This is what I thought.^
It appears the gas check helped expanding the neck though. Kinda preventing the bullet from getting squeezed down. I need to check 30-30 with and without gc and see if it makes a difference. Next time I cast some up I’m going to measure. Right now all my 30 calls are lubed and checked.

[Larry Gibson]

On the GC'd 311041s, yes, the GC is expanding the neck as the bullet is seated.

With that minimal neck tension on the 44 bullet a good crimp will be needed or the bullets will seat deeper because of spring tension and/or recoil in the magazine tube.

[charlie b]

So, how much neck tension is desired in a rifle?

I have good luck without an M die in the .308 with gas checked bullets, but, not with plain base. Am using the Lee collet neck size die. I suspect the PB bullets are being sized down a bit.

What size expander should I get from NOE? I size the bullets to .309 (they are powder coated prior to sizing) before loading.

[Dman75]

I thought 3 thousandth neck tension will a decent crimp would suffice on the 44 mag. Am I wrong about this?

[Larry Gibson]

.003 is good if that's what you're getting. Still need the crimp.

[Dman75]

Thanks Larry. Always learning something when it comes to casting. Definitely a different world from jackets