Hornady vs Lapua and Velocity

[Nimrod]

I learned something in regards to performance differences between the same loads in Hornady vs Lapua brass. I ordered 300 of the once fired Starline brass from Performance Arms and got about 100 pieces of Lapua brass mixed in. I decided to see how they would mix in with my normal brass so I shot them over my chrono next to my normal load with Hornady brass. I am getting 50 FPS less velocity with the Lapua, same bullet, same load, same powder, only difference is the brass. I decided it had to do with the flash hole being smaller so I drilled out the flash holes on ten of the Lapua brass and reran the test. Got the same results except the Lapua loads ran about 40FPS slower this time. Not sure what piece of the recipe I?m missing but there?s no doubt the Lapua runs slower.

[drewsbow]

neck tension ?

[A5BLASTER]

It's because of the thickness of the brass in each diffrent case.

Each case has a diffrent case volume due to brass thickness.

[Nimrod]

That?s probly it, I was surprised at the difference between the two brands.

[BobinNC]

Weigh the cases. That will tell the tale.

[Nimrod]

Hornady is averaging around 120gr, Lapua is around 114gr.....so the lapua case is thinner meaning with the same load as the Hornady it isn?t as ?full? so slightly less pressure.

[Mad Charlie]

I recommend checking the water capacity of each brand of case. With the cases fired in the same chamber, unsized, and the same length.