Warning

 

Close
Confirm Action

Are you sure you wish to do this?

Cancel Confirm
AR15.COM
Armory Sponsor
6/28/2009 4:00:07 PM EDT
When I neck size my brass, how much less should the inside neck diameter be than the size of the bullet?  I compared the difference between different neck sizing dies and got different readings.  The Redding dies averaged about .003 to .004 less than the bullet diameter.  The Lee Collet die I was using consistently measured .002 less than the bullet diameter.  Is the .002 enough neck tension to safely shoot?  I typically don't crimp my cases, but rely on the neck tension.
6/28/2009 4:30:30 PM EDT
[#1]
It all depends,... but I would bet even the 0.002" is totally adequate.

Measure the neck OD of the loaded round.  Measure the same for a case.  The difference sholuld be in the 0.002" to 0.003" range.  0.004" is not too much but is likely unnecessary.

Take the loaded round in your hand and push the tip inot a wooden bench top surface and try to push the bullet in.  If it moves, there's inadequate tension.  If it doen't move, you are good to go.
6/28/2009 4:45:16 PM EDT
[#2]
If the neck is clean inside, .001" is fine.
6/28/2009 5:18:36 PM EDT
[#3]
The bullet expands the neck to about 0.001" less than the bullet diameter.  This is due to spring-back.
6/28/2009 5:35:55 PM EDT
[#4]
Quoted:
The bullet expands the neck to about 0.001" less than the bullet diameter.  This is due to spring-back.


+1

To cover errors in neck measurements, wear in tooling, mfg. tolerances, etc., most folks will go a little high, maybe .003.  It can be shown that  after .001 or .002 interference fit on the diameter, the annealed soft neck material exceeds yield anyway.

6/28/2009 5:38:14 PM EDT
[#5]
My neck size is about 19".......
Armory Sponsor