Need help ! seating with new Lapua brass

[ibbuckshot]

Being a newcomer to rifle loading I want to know if I can load "new" Lapua 6mm Br brass with out running it through a size die first?? I am seating Sierra 107gr match kings and find a great deal of pressure needed to seat using a new Wilson seating die and a K&M arbor press. On some, just before the end of the seating stroke there is a snap sound caused by the release of pressure as the bullet pops into the casing the rest of the way sometimes causing the oal to be a 5 or so thousands too short. I have used a kinetic puller to streach them out and reseated them to proper oal. After doing about 8 loads I stopped to write this to find out about the sizing question. Sure would like to hear some feedback. Thanks.
Have fun,
buckshot

 

[Forum Boss]

Yes, so long as the brass will chamber in your rifle, you can load without putting the brass in full-length sizer.

I have the same seating set-up as you do--Wilson Microm. top seating die and K&M Arbor. The K&M has barely enough leverage to seat bullets in fresh brass--but that's because the neck tension is too great on brand new brass. I suggest you get a K&M or Sinclair Expander mandrel and run that in the neck once before your first load. You'll find the bullets seat MUCH easier. Also, this irons out any dents in the neck.

Also, once you reduce the neck tension, you will get much more consistent results with seating depth, and the seater stem won't engrave a circle in the jacket.

I put a very tiny amount of Ballistol lube on the expander before I run it in the necks. Ballistol is a very light lubricant, but very slippery. Just a whisper of lube is all you need.

 

[rstreich]

If you use a stock expander mandrel to open the necks up, you'll want to size the necks down to the neck tension you want. There's little or no neck tension when you run the expander mandrel in.

You could take some emery cloth and a drill to knock a thousandth or two off the diameter of the mandrel also.

 

[Hipshot]

Randy, that's a great idea. I read your info and smacked my forehead.....I could have had a V-8

Now for loading new brass...
If all you're going to do is fire for sizing/resizing and not for checking statistics or accuracy, I just load em and don't record anything. The reason is that the first shot in those cases will not be like any of the succeeding loadings so the information received is of no value.

IF, however, I'm interested in velocity, accuracy, etc. on the first firing, I'll prep the brass, primarily around the neck and mouth so that these first cases will have the same neck tension and will open up the same as they will in their later use.

 

[Forum Boss]

If you use a stock expander mandrel to open the necks up, you'll want to size the necks down to the neck tension you want. There's little or no neck tension when you run the expander mandrel in.

You could take some emery cloth and a drill to knock a thousandth or two off the diameter of the mandrel also.

Re necking down the brass again--it kind of depends on the diameter of your expander and the diameter of your bullets. With NEW unturned Lapua 6BR brass and my K&M expander,used with the K&M neck turning tool) the tension is just fine after expansion. There's enough springback in the case to give .001+ tension.

But YMMV with different expander mandrels, and once the brass has been fired of course you'll need to neck size or FL size.

 

[trgtsnpr]

ibbuckshot
check out stephenperrys thread called "competition BR loading - newer stuff" he will start you out at the begining to the end it's a great thread imo bill