The terms "low brass", "high brass", "low base" and "high base" have absolutely nothing to do with pressures. "High brass" and "low brass" had to do with the quality of the cartridge case back in the days of paper cases and fiber base wads and today is really mostly a marketing thing. "High base" and "low base" really have no meaning today. Those terms dealt with the height of the base wad in whether the cartridge case was made for loading with bulk smokeless powders or dense smokeless powders. The "high brass" shells were Western's RECORD, Winchester's LEADER, Rem-UMC's ARROW, etc. The "low brass" shells were Western's FIELD, Winchester's REPEATER, Rem-UMC's NITRO CLUB, etc. All of these cases were made with a "low base" for loading with bulk smokeless powders or a "high base" for loading with dense smokeless powders.
Virtually all of the promotional loads sold by the big chain stores are loaded with the smallest amount of the fastest burning powder they can use and stay within SAAMI specs, meaning the pressures are right up there at the max.
