From article by John Linebaugh with pressure data to back it up
Quote
In a technical sense the .45 Colt is a big caliber, large capacity case that must operate at low chamber pressure compared to many magnum rounds. The fact that it has more capacity allows this to happen. In general loadings the .45 Colt will do anything the .44 magnum will do with about 6000 to 10,000 CUP less chamber pressure, depending on the load and bullet weight used. With standard weight slugs the difference is not as wide as it is with heavy slugs. This is the same rule that applys to calibers in rifles. A 250 gr slug is unheard of in a 7 mm mag, but neck the same case to .338 and the 250 gr slug is perfectly balanced. But like magnum cartridges the secret behind the .45 Colt's potential is the powder used to drive the slugs. For years Hercules 2400 was considered to be the finest magnum handgun powder available. Pressure data has shown that this is not true and the finest sixgun powders available today for heavy handloads are Hodgdon's H-110 and Winchester's WW-296. These powders are basically the same and can be fully interchanged as to charge weights. I've probably shot over 50 lbs of WW-296 in all my testing and twice that much H-110. I feel H-110 is kinder to lead bullets than W296 but H-110 does vary from lot to lot more than W296. I have never seen a "hot" or fast can of H-110 but have used some that was a grain or 2 slower than normal. The only way you can tell this is with Pressure equipment or a chronograph. With these powders VELOCITY MEANS PRESSURE. If you're not getting normal velocities, your powder is slow and not generating normal pressure. By working up carefully 1/2 gr at a time till your normal velocity is acquired you can continue to use these slow cans of powder. NEVER EXCEED OUR RECOMMENDED VELOCITIESOCITIES
