300 NM Neck Tension Bushing

Ornery

Full Member
Aug 13, 2010
135
3
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67
S. California
#1
For Petersens or Lapua brass, what size die bushing are you using? I will probably go with the Forster S neck sizing die. My initial measurements on the new brass have it around .338 OD.
 

MagnumManiac

New Hide Member
Jun 18, 2018
5
1
3
#2
Firstly, where did you obtain Lapua brass in 300WM?
I have some (300) from the 1980’s, yet to lose a single case to splits or loose pockets in the 50 I use in F-Class Open.

My necks are skim cut to .0145” and I used a .336” -.335” bushing when I was using bushing dies.

Cheers.
:)

Edit to add.
Just checked my notes on the Lapua brass, it measured .0145” when cut, but was around .016” prior to trimming. Bushing sizes are .332”-.333”, not as stated above.
 
Last edited:

mijp5

Gunny Sergeant
May 7, 2009
3,958
992
113
#3
Firstly, where did you obtain Lapua brass in 300WM?
I have some (300) from the 1980’s, yet to lose a single case to splits or loose pockets in the 50 I use in F-Class Open.

My necks are skim cut to .0145” and I used a .336” -.335” bushing when I was using bushing dies.

Cheers.
:)

Edit to add.
Just checked my notes on the Lapua brass, it measured .0145” when cut, but was around .016” prior to trimming. Bushing sizes are .332”-.333”, not as stated above.
He said NM, not WM
 
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mijp5

Gunny Sergeant
May 7, 2009
3,958
992
113
#5
For Petersens or Lapua brass, what size die bushing are you using? I will probably go with the Forster S neck sizing die. My initial measurements on the new brass have it around .338 OD.
If you have the brass in hand, do you have any bullets you can stuff in there and see what the tension actually is? Otherwise, factory brass usually comes ready to load, which should give you at least 1-2 thou. A 337 or 338 bushing would work
 

Ornery

Full Member
Aug 13, 2010
135
3
18
67
S. California
#6
If you have the brass in hand, do you have any bullets you can stuff in there and see what the tension actually is? Otherwise, factory brass usually comes ready to load, which should give you at least 1-2 thou. A 337 or 338 bushing would work
Sounds like a plan. I have bullets and brass, but I did not have any dies yet. Will receive 300 NM dies this week.

Thanks.
 

mijp5

Gunny Sergeant
May 7, 2009
3,958
992
113
#7
Remember something though. I hear the Petersen brass is pretty thick. If you use another brand, the bushing will likely have to be smaller
 
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