I recently chronoed some 6PPC loads with Lapua and Sako brass, using the same load and found that the Lapua brass gave inferior MV by about 59fps on average compared to the Sako. The load was 26gn of VV N130.
I am fairly sure the Lapua brass has a slightly higher capacity.
Could it be that the Lapua brass generates less pressure hence the lower velocity?

Just an interesting quirk I thought I'd put up.

Incedently I haven't noticed a great difference in accuracy, if anything the Sako brass does better even though it's weight varies more and the individual cases ay have a different number of previous firings.

The smaller the capacity, the higher the pressure...and velocity

Express

SAKO 6PPC brass has less capacity than PPC cases fire-formed from LAPUA 220 Russian. As pointblank said, with the same load the smaller case will give more velocity but at a higher pressure.

Your experience with SAKO brass is different than the vast majority of Benchrest shooters in the United States. I don't know anyone who still uses it. LAPUA brass is so much better that it isn't even a contest.

Ray

I am assuming you are speaking of Sako PPC USA brass. This brass was introduced when Sako offered their varmint rifles in the 22 and 6 PPC. This brass showed up after the long drought following the discontinuance of Sako 220 Russian brass. BR shooters bought it and quickly learned that it did have less capacity than the old brass. It did not hold up as well either. Thankfully Lapua and Norma got their new brass on the market shortly thereafter. As Ray said earlier, the new Lapua is so good that trying any other is a waste of time.

hmm...better to be lucky than good?

When I got the Lapua brass I chucked all my Sako brass together, therefore loosing track of how many times each case had been fired, and what the weight of each case was.
Then I realized I didn't have a 6mm mandrel for my neck turner and had to go back to using the Sako stuff. I didn't sort it.

That Sako brass has been through a lot of fireings (maybe 20's for some, les than 10 others) and I have only thrown away cases with split necks and yet it still shoots groups in the .3's consistently, .2's on good days.

I don't compete with this rifle and I realize that it may not be competitive, but it's a varmint rifle that I use for hunting and culling, so it is very very satisfying to shoot.