During load developement for my 6.5 Gibbs, I had pressure problems before I should, The culprit was uneven neck thickness, after turning the necks to an even .011 thickness, they have subsided somewhat, Now my ?
on the initial neckdown from 270 to 264, I only end up with a false shoulder part of the way around the neck, Is this normal. As you can see in the accompanying pic, the third case from the left, the false shoulder is missing from the right side of the neck and the neck looks visibly crooked.
In your best opinion is it a die problem or something that normaly occurs when using a full length die to neck down. Do I need a bushing die? will a 6.5/06 AI bushing die work or do I need to have one reamed?
Thanks for sharing your knoledge
RR

Are you using your Gibbs die to form the neck? Your case is leaning to one side as the neck is formed. It should not be a real issue when you fireform.

I have my own Gibbs+ built from blown out 280 cases. In my 280PDK I would expand to 308 then back down. They were never perfect. Using a factory 280 die for the neck down helped. But I never really had an issue with either after fireforming.

I've never used a bushing die so I have no comment. Other option would be to stick the bullet in the lands for forming.

yes, I'm using a redding FL sizer to neck down, I have one caliber which I use a bushing die to neck it down with, It uses 5 bushing steps to neck a 338 Lapua Mag. down to .284.
The rest of my case forming has always been done with FL sizers. I've necked 50 AE basics down to .458, 8mm RM down to 7mm STW, 444 marlin down to 375, formed 30 Herretts, 7mm JDJ's, all on the same press, and never had this problem before.
I have also noticed that my necks come out thicker on the gibbs if I FF with cornmeal, opposed to bullet and powder.
RR

In the case of a 8mag down to the 7STW your case is the same you are just necking down. In a Gibbs the die is larger than the case allowing it to lean off center.

I used the COW method for awhile. Then I cut the case open. I found that the head area was thinner than with a case formed with a bullet. Different pressue wave and timing???? More brass moved to the neck area???? I now only use a false shoulder and a bullet. With my 340PDK I now just neck it up to 338 and stick the bullet in the lands. Lost my 358 expander and just to lazy to buy another one

Here is my version in 280 & 340. I used the 280 case and 40deg .458 shoulder. I have it in 6.5 as well.