Another neck diameter question on brass. Sorry

[Thumper580]

I measure the neck OD on a piece of fired brass from my LR308 and it is .340. To resize a semi auto about .003, I should use a .337 bushing? Correct. The ID on the same fired brass is about .310. Will the .337 bushing reduce the ID enough to properly hold the bullet with enough tension. I'm using the Redding type S Full length die.

Been reloading for 30 years and the light bulb is finally going off!!!

NEVER MIND! realized I had it wrong.....Need to measure loaded round. Thanks for the clarification below.

 

[justinbaker]

I measure the neck OD on a piece of fired brass from my LR308 and it is .340. To resize a semi auto about .003, I should use a .337 bushing? Correct. The ID on the same fired brass is about .310. Will the .337 bushing reduce the ID enough to properly hold the bullet with enough tension. I'm using the Redding type S Full length die.

Been reloading for 30 years and the light bulb is finally going off!!!

What you need to know is the size of a loaded round. Then subtract from there

 

[mdmp5]

In case you are looking for more advice, forget the inside diameter of the mouth, which you cannot measure accurately anyway with a caliper. That data won't tell you anything useful. Just worry about the OD, which should be 2-3 down from your loaded round.