Norma brass 300wm

[shocking300]

I have shot thousands of 300wm rounds, someone said to try norma brass, so today ran it through chrono and same charge it was 150 fps slower , it was new and not fireformed. Is that normal ? My understading is norma has less volume so higher pressure to be expected with same charge. 300wm The load is 74.7 H1000, 225HPBT Vel 2610fps with norma, winchester 2760fps same charge. Thanks

 

[Greyfox]

Did you chronograph your Winchester loads at the same time as you did the Norma?
I use Norma brass and just got some Winchester which I haven't loaded yet. I didn't measure the case volume but when I went ti trim the Win brass using my Wilson case trimmer, the Winchester brass was too small to be held in position by the dye holder. It's narrower then the Norma and the thickness is the same at the mouth. I'll have to compare the volumes. I would have thought the Norma had more volume.

 

[shocking300]

Did you chronograph your Winchester loads at the same time as you did the Norma?
I use Norma brass and just got some Winchester which I haven't loaded yet. I didn't measure the case volume but when I went ti trim the Win brass using my Wilson case trimmer, the Winchester brass was too small to be held in position by the dye holder. It's narrower then the Norma and the thickness is the same at the mouth. I'll have to compare the volumes. I would have thought the Norma had more volume.

I chronoed the loads minutes apart. Let me know how the volume measures up. Thanks

 

[Greyfox]

I chronoed the loads minutes apart. Let me know how the volume measures up. Thanks

I just measured the capacity of the Winchester and Norma, new, unfurled cases using Retumbo powder filled to the mouth. The Norma case is 88.3gr, the Winchester is 83.4gr. The Norma holds 4.9 gr more powder. This is likely where your velocity went. As mentioned, the Norma case is dimensionally fatter.

 

[shocking300]

thank you sir that explains a lot