What would cause this

[GT Accuracy]

Using the 21st century lathe to do some neck turning and I am getting to the point where I hit the neck shoulder junction and its digging in only on one side causing a half moon shape

Video here


http://youtu.be/QD9QkD_CVlk

 

[DHD]

Have those cases been fireformed, or new unfired. I had some that did that, but they were 308 cases resized to 6.5 Creedmoor, so they were not perfectly straight to start with. After they were fireformed, I turned them again (with no adjustment to the cutter) and then I had a perfect cut.

I only have/use the 21st Century stuff.

 

[GT Accuracy]

they are brand new, unfired

however they are 7x57 brass in the final stage of the formation process to make 6mm AI brass


Greg

 

[fdshuster]

Greg: I've sometimes had the same problem with an occassional case (Lapua) that may not have a perfectly straight neck: the cutter will take more off one side of the shoulder than the other side.

I've since started using the 40 degree cutter on my 30 degree case shoulders ( ppc & BR), and had no further problems.

 

[GT Accuracy]

Huster

thats what i figured...thus i am using a 30* cutter on the 7x57 brass which i think is 20* stock

 

[GT Accuracy]

any more thoughts on this before i let it go to the back pages?

seems it has to be a non-straight case issue