Thread: First attempt at necking down 308 to 7mm08

Well guys I had a go at this and didn't have any luck.

I got a few bits of that 308 brass I've got, put a tiny bit of lube on them, and slowly pushed it into the pull length 7mm08 sizing die.

I couldn't close the bolt on my rifle with any of the necked down cases. I also noted the necked down cases are a little bit shorter than the length I normally trim too. Not being able to close the bolt is a little concerning though and I didn't want to force it obviously.


I measured the outside neck diameter of the cases:

Once fired, fully prepped 708 case:
Outer width: 7.81mm
Neck width: 0.31

Once fired, fully prepped 308 military case #1:
Outer width: 7.96mm
Neck width: 0.41

Once fired, fully prepped 308 military case #2:
Outer width: 7.99mm
Neck width: 0.44

Once fired, fully prepped 308 military case #3:
Outer width: 7.94mm
Neck width: 0.41

It's a bit weird the necked down cases are wider.

You can see the actual necks are visibly thicker on the necked down cases (to be expected I imagine... probably need to be reamed out from what I hear).


And you can see the shoulder isn't quite right (necked down case is on the left)





You can tell the third case is the 7mm08 one


Where am I going wrong chaps?