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Load formulas - starting in the middle?
- Thread starter mpmo
- Start date
Ok. Results are in. No overpressure in either handgun. A bit more PF that what I'm looking for, even at the minimum recommended powder levels. Got a few more questions about where to go from here.
1.PF for 125gr Sierra FMJ RN at lowest grain was still average 135 in one gun and 130 in the other. No feed or cycling issues. Can I go below the recommended starting grains now to try to get closer to 125?
2.I noticed less velocity on the first round fired pretty much everytime I started with a new test. More so with the cold barrel. Should I throw this data out? Why would this occur.?
1.PF for 125gr Sierra FMJ RN at lowest grain was still average 135 in one gun and 130 in the other. No feed or cycling issues. Can I go below the recommended starting grains now to try to get closer to 125?
2.I noticed less velocity on the first round fired pretty much everytime I started with a new test. More so with the cold barrel. Should I throw this data out? Why would this occur.?
Aguila Blanca
Staff
What was your minimum velocity and power factor? What was your extreme spread ... and how many rounds did you run through the chronograph?momo said:1.PF for 125gr Sierra FMJ RN at lowest grain was still average 135 in one gun and 130 in the other. No feed or cycling issues. Can I go below the recommended starting grains now to try to get closer to 125?
It must have been in one of your other threads where I quoted the IDPA rule book on how they test ammo for power factor. This is the protocol for larger matches, like regionals; I don't know if any clubs bother at their regular competitions, but you might as well have ammo that you know will always pass if you happen to shoot a big match.
You show up ... they pull three rounds at random from your ammo box/bag and shoot them over the chronograph through your gun. Two of the three must make the minimum power factor. That means, depending on the extreme spread, an average of 130 or 135 might not be good enough because you can't count on the random pick getting rounds that are near the middle or high end of the pack.
For this purpose, I want to know that the worst round will make power factor, and then try to minimize my extreme spread so that the faster ones aren't a whole lot faster. If you'll be alternating guns for competition, you also want to be sure that your worst round will make power factor in the slower gun.
What were the slowest velocities you recorded in this round of testing?
What was your minimum velocity and power factor? What was your extreme spread ... and how many rounds did you run through the chronograph?
What were the slowest velocities you recorded in this round of testing?
Bullets are in short supply and I just wanted to get some data for a starting point so I just loaded 4 rounds (2 rounds per gun.) at each of the powder levels. So obviously, it's not going to be good enough. But once I get in the proper range, I can load more which will show a better average. That being said. Also, I assume with these results and assumed going in, I will have a different formula for each of the guns.
At lowest powder level loaded (book spec minimum):
Gun 1: 129-131PF, 1034-1049fps
Gun 2: 133-137PF, 1060-1097fps
I'm not too concerned right now about making exact power factor. I doubt they will be testing rounds at the local level matches I'm going to attend. And the league I shoot in doesn't have any PF restrictions. But I want to be pretty close. I'm going to shoot for 126-128. I'm sure if I ever made a regional match, I will have to change some things.