Was loading up some more .38 for the target pistol. After loading up about 30 rounds I started weighing them. Noticed from 1-3 10th of a grain difference. Since I had the same load prowder, same bullet and primer thought the only big difference was brass. Took 3 brands, Winchester, Remington, and Blazer. Made sure all where same length. And yes, different brands weighed different. Remington was lightest, Winchester and then Blazer the heaviest. Has to be the thickness and composition of the brass. Since all were sized the interior has to be of a different volume. With the same loads of powder, bullet, and primer all three will produce a different Pressure....therefore affecting performance. In using the three brands, and I keep them separate when shooting, In my gun the Blazer brass shoots better than the other two. In the Carry .38 with different bullet and load the Winchester is best.