Doughnuts??

[terryh]

As per title, what factors contributes to or accelerates them forming?

loading techniques? Cartridge itself  e.g high ‘intensity’ design, brass make etc.

cheers Terry

[jcampbellsmith]

I'm fairly sure the donuts on my 260 Rem brass appear when I resize the brass.

Regards

JCS

[No i deer]

I think the brass that moves forward on every firing as it stretches and builds up at the neck/shoulder junction and when you resize it squashes it inwards and brass becomes thicker on the inside, what I don't understand it doesn't always do it. I neck turned all my 284 brass and most of it has been fired 10 times and not a single donut and I use 180gr scenar l's for target and 162gr amaxs for hunting,the scenars sit well in past the donut area as it was throated for the 180gr hybrids which also suits the 162gr amaxs.

I've got donuts in some well used 7mm saum brass I inherited with the rifle, I guess the case prep was done exactly the same way,

I think I even re-neck turned them once,I did have a 7mm inside neck reamer and sold it and my brass as never had donuts then I discovered some recently in these cases,still awaiting a new one I ordered from spud 2 months ago...

[Guesty]

From my own experience I'm inclined to believe that neck doughnuts are a feature caused by neck bushing dies. I have returned to collet neck dies and honed FLS dies and the doughnuts have gone.

[No i deer]

Both my 7mm dies are FL bushing dies