Rubber O-ring under locking ring or not?

[lurcher]

I have read that some people advocate the use of a rubber o-ring under the locking ring on their sizing dies. The idea being I think to introduce a little slop in the system so the brass aligns nicely in the die rather than being forced off-kilter.


Aside from Lee Collet neck dies which come with a factory fitted O-ring. I have not tried this. What do you guys think, is this a good idea or a waste of effort?

 

[BoydAllen]

All of the Lee dies come with O ring lock rings. I think that they work. The only disadvantage is that they make it easier to loose your die setting. I fixed this with an index mark on the die that lines up on the press, and a regular lock ring above the Lee, to keep it from moving. Just remember not to screw the Lee rings down till the metal on the outside hits the press. This negates that advantage of the O ring.

 

[Steve Blair]

The Forster Co-Ax press also operates on a similar principle, allowing the die to self-align in the press slot.

 

[ordnancemarine]

I do it and I get excellent results... solved my run out problems.

 

[bigedp51]

accurateshooter has more than just this forum with very good information.

"All the information in the world is written in books and all you have to do is read"
Attila the Hun
(or was it Hellen Keller?) :

http://www.accurateshooter.com/technical-articles/reloading/o-rings-on-dies-may-reduce-run-out/

 

[K22]

I used it under the sizing button stem rather than locking ring for a 308 and it reduced the run out.

I think I read that technique somewhere on this web site several months ago. Anyway it seems to work well

 

[Scott Harris]

Use it with a Harrell's turret press and it seems to work well. I make sure to have a little camming-over as part of this process.