It’s very common knowledge that their book data is heavy conservative. I use hodgdon as they make the powder and have a wider range of load data. I’m not going to do a full Benchrest copper solvent flush every 25 rounds down the pipe lol. I’m not a moron I’ve been reloading over 10 years. First I’ve come across this issues. My load is not hot and my load is not compressed. Ordered a bore scope today and I’m waiting on that and double checking my bullet jump after that shows up. If I had to guess I have little roughness in the end of the throat yet and I’m getting a lot of copper yet…
Actually, Hodgdon is about the only published data that actually publishes pressure AND charge data. As such what they publish is most probably actual test data. You will also note that the published loads may or may not be at SAAMI maximum, but will not exceed it. While it may appear that the data is conservative, that is actually the usual case since the data is obtained in SAAMI specified test equipment that uses a mimimum chamber dimension. This minimum chamber is usually smaller than actual commercial (off the shelf) rifle chambers. This is by design to insure that the pressure will not be exceeded in any commercial firearm.
Hornady fully describes their method of presenting data in their manual and often takes much heat over their "conservative" data. In this case they test most loads to SAAMI and determine the maximum load for given cartridge based on pressure. They then fire the loads in an actual rifle to obtain the velocity data and then publish the data as velocity versus charge. As a result their data will always (or at least almost always) yield lower velocities as compared to Hodgdon or Sierra.
Sierra 6th Edition appears to be predominately based SAAMI method testing with velocity data obtained the SAAMI test barrel and chamber. Earlier editions were based on data from actual rifles.
Based on info provided to me by Berger, their data is derived from Quickload. I was surprised by this but that is what they said when providing me a page from the manual.
Some early reloading data in published manuals was based on determination of loads using the traditional signs for pressure and setting the loads based on that data.
The end result is that the published data in everyone's manuals should be at or below maximum pressure when fired in commercial rifles with SAAMI minimum sized or larger chambers. Those loads should typically not result in pressure signs. However, specifically related to brass and primers it is possible to see indications of pressure due to those specific items, such as case head expansion on soft brass or use of a Rem 6-1/2 primer in 223. Obviously the data collected was with specific lots of powder and components so some variation can be expected due those differences. Chambers that are not standard (custom) are a different animal. When the data presented is by velocity the maximum charge is likely less than the actual maximum charge since the data works in specific increments ( ie max velocity in table is 2700 but actual max pressure data was 2740 and the table increment is 50 or more).
When you load and begin to see pressure pressure signs it is almost a certainnty that you are above the SAAMI maximum pressure and you are at the pressure limit for the component that is showing pressure.
Maximum load is a term often used in load manuals and in most cases it is the Maximum load that the specific manufacturer determines to be a safe load. It may or may not be at maximum SAAMI pressure.
