Among Starline, Winchester, Federal, Remington, MagTech, and other European manufacturers of 45 Colt cases, I am nearly certain that Starline brass is the thickest. Among all the rest, which is thinnest? I ask because in Venturino's Shooting Lever Guns of the Old West, the author wrote that when shooting black powder loads in 45 Colt rifles thick brass such as Starline's will have insufficient spring or give to seal the rifle's chamber from gas blow back - aka crud or schmutz.
The large number of Starline 45 Colt brass I have works beautifully when coupled with H110 and CCI Magnum primers. I want to acquire brass that will be thin enough to seal my rifle's chamber when shooting lower pressures of black powder.