Re: Different brass = different results?
As a general rule, reloaders don't mix brass. With pistol reloading, it probably doesn't make that much difference. But in rifle reloading, where accuracy is everything, brass from different mfgs can make a big difference. Although the outside dimensions of caliber-specific brass should be the same, the interior space varies greatly from one mfg to another. I had a 25-06 where I could use both Win and Rem brass and it didn't matter with the load I was using. But with my 6.5-06 AI, changing brass changes thew whole equation.
Lapua brass is best known for great uniform quality and strength. Depending on the caliber in question, Lapua brass will generally have a few grains less capacity than Winchester, Federal or Remington (again-depending on caliber). Using the load you developed with Remington brass will probably result in higher pressure when used in the Lapua brass, which will change barrel harmonics and accuracy. I know some benchrest shooters that won't even use brass from the same mfg, unless it is of the same lot number.