OzFclass

Hi All,
With the neck turned cases I have for my 284 do they thicken after use?
I am just running some back through my K&M set up to remove the donuts (dose this matter if the bullet doesn't contact it?) and it has taken some more off the outside of the neck.
Any thoughts?
Hope I haven't done any damage.

Tim N wrote:Hi All,
With the neck turned cases I have for my 284 do they thicken after use?
I am just running some back through my K&M set up to remove the donuts (dose this matter if the bullet doesn't contact it?) and it has taken some more off the outside of the neck.
Any thoughts?
Hope I haven't done any damage.

Brass can flow from the shoulder through to the neck on firing, resulting in some thickening of the neck. Some believe that using a standard FLS die before neck turning will reduce donuts forming - a bushing die will not size the neck right down to the neck shoulder junction and the small collar that is left unsized can increase the risk of donuts.

Also, when neck turning, cut about 1/32 into the neck shoulder junction.

Does it matter if the bullet doesn't contact the donut? - depends whether it impacts the gas flow. But, once identifed, easy enough to remove and one less thing to blame next time you have a flyer.

Thanks ND
For anyone interested I have just been informed by someone respected in the industry that once necks have been turned leave them alone.
I now have 10 cases for fouling shots

Im assuming your chamber has a 313 neck which would make your cases around 307-308 unloaded and requiring neck turning to fit.

When you do your initial neck turn, do you cut into the shoulder a little to remove that brass that flows into the neck?

If you have a 317 or 318 neck you dont need to neck turn and you can get away with inside reaming with a proper donut cutter tool. I will be doing this as I have a 318 neck. Ive done the working out and if I size with an intermediate size bushing say around 316/317 (I use 311 for neck sizing to seat the bullet) then I should have the perfect fit on my wilson inside neck reamer to cut the donut out without removing any of the neck. From what I have been told the donut will occur after a few firings and I just have to keep an eye on the cases to see if they re appear. At this stage I was thinking check every 3-5 shots. With a hybrid touching the rifling the bullet is clear of the neck/shoulder junction in my chamber. I know the final seating depth is yet to be determined with this barrel so it could be 20 thou further in or 15 thou further out, or if it prefers the VLD's then it may be different again.