Thank you everyone for your help and input.
Before I start to ramble, and y’all have no idea what I trying to say, here are the questions I am trying to get answered in my post below:
1) How do I see signs of too much pressure? (Remember, I am brand new to this and have a pretty thick skull)
2) Do I use the FMJ or HAP C.O.L for my JHP's? I know it's only a difference of .031 but does that matter?
3) Are you tired of my questions yet?
Here we go....
I spoke with a live person at Hodgdon today and I am beginning to get a better understanding.
He told me that I can use any load data for flat nose, jacketed or JHP for my 125 Gr. 9mm JHP.
That part I understand now. 125 Gr. is 125 Gr. As long as it is the same type of bullet.
What I don't understand is COL. He suggested I use the data on their site for the Sierra FMJ- Okay so far- Starting load at 3.0 to 3.6 max
What I don't understand and didn't ask because I didn't think of it until after I got home and pulled up the load data is the COL.
If I am using JHP isn't the bullet profile different for JHP than FMJ?
Example using the Hodgdon website data- for 9mm 125 Gr.
FMJ = 1.090
HAP = 1.069
If it is the same bullet, why the different COL?
If 9mm is such a high pressure load, doesn't it matter if I shorten the COL? I know both my Glocks will cycle 1.140 COL no problem, but why would I start long and work my way down? (Some have suggested I start at 1.120 and work my way down) BUT- how do I know where to stop?
I don't have a chronograph but I am trying to find one. I am guessing that would be the ideal way to figure all of this out.
What are the sign of too much pressure? How do I know too far before it happens? -Yes, I know not to go shorter than the 1.069 and actually that's what I loaded my original 18 test rounds to.
For such an exact science I m not feeling very, well, um, exact.
Thank you again for listening,
Brad