RedHawk357Mag said:
But what is mystifying me is this Chronograph data. SD ES and whatever other little abbreviations this wonder box can spit out or I can get MS Excel to tally for me. So what data do I use to develop "the load" for this RedHawk?
You can enter all of your velocities into Excel and use that program to generate as much information as you need ... that's what I do. Generally, chronographs process the measured velocities to give the following:
HI = High > highest velocity
LO = Low > lowest velocity
ES = Extreme spread > difference between fastest and slowest velocity
AVG = Average > average velocity
SD = Standard deviation > how much your velocities deviate from the average
Ideally, you want the ES and SD values to be as low as possible but the average depends on what you want out of the load. Some folks load to achieve a specific average velocity, most likely because they're after a specific bullet energy range for hunting or some other application. Others load for accuracy and just want to know what the average velocity of the most accurate load is. Some are after a combination of both. For handgun loads, I would think that most folks are after consistency so ES and SD are more important to them than average velocity assuming that the AVG is acceptable. Chronographing rifle loads is a little more involved in terms of the objectives and variables.
As for your loads, what are YOUR objectives? Are you trying to find the most accurate load, fine tune your loads for consistency, achieve a certain velocity without leading, are you concerned about recoil, excessive pressure, are your loads within published "safe" ranges? Hodgdon lists a load range of 4.5 to 5.0 grains of Tightgroup for the 158gr LSWC with a maximum velocity of 1108 fps at 24,900 CUP so your starting load seems to be on the low side at 3.8 grains particularly since you have a Redhawk. The SAAMI maximum pressure rating for the .357 Magnum is 35,000 psi which is about 34,895 CUP if you use the conversion formula
here but the Speer #11 manual lists the SAAMI working pressure as 46,000 CUP. All of the loads in Lyman's 49th edition are under 45,000 CUP with the majority being under 42,000 CUP.
Basically, if you load within published limits, chronograph data can help you improve your loading techniques, loads, and/or components to reduce ES and SD values. This can become an obsession all by itself which can bring both pleasure and pain. If you're pushing the envelope and developing loads outside published limits, a chronograph can help to give you some idea as to how far over the line you are.