Case capacity and velocity...

[20PPC]

I recently switched all of my 30 BR brass over from Lapua to Peterson.
Having tried it last year in one gun I found it had substantial reduced case capacity .
In working up new loads I found I needed to reduce the charge but ended up extremely surprised in the gain of velocity much more than expected.
With Lapua and a charge of 35.1 velocity was around 3060 + - with the Peterson brass and a charge of 34.2 I'm getting 3135 + -.
The normal nodes for the 30 BR are 2950 and 3050 I'm having no problem shooting X's at 3135 fps but groups are not as good as I'd like.
Back the load off or not ?

 

[riflewoman]

Won’t know until you try.

 

[PigButtons]

^^^^ what she said.

 

[RegionRat]

Yup, what she said....

 

[mikecr]

Do you have QuickLoad? Is there another powder to solve it?

 

[20PPC]

I also have N130 and the numbers are almost the same.

 

[Straightshooter1]

I recently switched all of my 30 BR brass over from Lapua to Peterson.
Having tried it last year in one gun I found it had substantial reduced case capacity .
In working up new loads I found I needed to reduce the charge but ended up extremely surprised in the gain of velocity much more than expected.
With Lapua and a charge of 35.1 velocity was around 3060 + - with the Peterson brass and a charge of 34.2 I'm getting 3135 + -.
The normal nodes for the 30 BR are 2950 and 3050 I'm having no problem shooting X's at 3135 fps but groups are not as good as I'd like.
Back the load off or not ?

Likewise, when I compared my .308 Peterson brass to my Lapua brass I found the Peterson brass to have .5 gr less capacity, which BTW corresponded to same kind of difference in weight too. And likewise, I got an increase in velocity with the Peterson brass where I adjusted the load down to get the same kind of consistency and accuracy I had with the Lapua brass. It didn't take much of an adjustment and didn't take long to find it as the difference was within a narrow band. So, yeah . . . I'd say to get your load better tuned, just back off a little, a little load developing, and see what you get.