Testing loads - Need a check list

I spoke (wrote) too soon. Here's the table for the velocity numbers I reported earlier and to which Unclenick referred. Note that the STI Guardian is a 5" 1911. The pistol in this test is a 4-1/4", Commander-size 1911. That helps explain why the same ammo has such different velocity in the two tests.

Ballistics_2.jpg
 
Does it say how many shots per test?

Since the table is at 15 feet, for the 9 mm you can add 5 fps for what you would measure at 10 feet, assuming absolute accuracy from the chronograph.
 
It only makes a difference if it means making power factor or not making power factor. For someone shooting one of the division that uses 125 as the minimum, if you load to juuuuust make 125 ... how much higher should you go to ensure that two out of any three rounds the match officials pull out of your box of ammo will make the threshold?
Click to expand...

what I was referring to is how many FPS would a bullet lose between five ft from the muzzle and ten Ft from the muzzle. I doubt it would lose even one FPS.

edit - well I was dead wrong on that one. I found some BC numbers from Hornady and plugged them into JBL. A 125 gn hollow point loses appx six FPS every five feet for the first fifteen feet
 
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Any ballistics program will tell you the answer. It depends on the velocity and BC of the bullet. In 9 mm firing in the 1100-1200 fps range, near the muzzle, a 115-grain HP bullet will lose about 1 fps for each foot of travel at near muzzle velocity. That's why I threw 5 fps in for chronograph distance differences (and another 5 fps for chronograph precision disagreements).
 
First test with the chrono all done. Got some good results. No indications of over pressure. Some of the brass ejected a few feet farther than factory as I increased the powder. I did notice on my Glock 17, that the ejection was inconsistent with both factory cci blazer and my handloads. Sometimes it would land 4 ft away, sometimes 8ft. Could be the shooter. ;)
I also noticed on the Glock 17 (Gen 5 Wilson Vickers) that the primer indentation has some deformation around the edges on all loads, my handloads, factory cci blazer and critical defense 115. The shape and deformation was consistent.
CZ TSO consistently spat the brass to the same locations and didn't have those primer marks.
 
The mark, if I understand your description correctly, is due either to a chamfer at the edge of the firing pin tunnel or to the firing pin tunnel being oversized. Either way, a gunsmith can open the tunnel and put a correctly drilled bushing in to eliminate that.
 
The rules I cited in post 14 are not the IPSC current rules. Indeed, I am not immediately relocating where I found them, but I'll leave the post up for anyone shooting a match with the other PF qualifying rule. The current IPSC rules say 8 rounds of a competitor's ammunition are collected at the beginning of a match. One bullet is pulled to determine projectile weight. Three are fired to determine if the average velocity makes the power factor the competitor is claiming. If they fail, three more are fired, giving the competitor a second chance to pass.

Statistically, that produces a different outcome from the rule I looked at. Suppose your average velocity was right on the power factor number. As you can imagine, a single set of three then has a 50% chance of passing or failing. But when you get a second chance, your odds of passing increase to 75%. This is because two chances have four possible combinations of passing and failing. Pass and Fail, Fail and Pass, Pass and Pass, and Fail and Fail. In only one of those four outcomes are both tests failing, which would have to happen for you to fail to meet PF. The other three give you one or two passing results, so with only one-out-of-four failing, your odds of failing are only 25%, so your odds of passing are 75%. What this means is that to have a 50% chance of passing from two tries, your average velocity will actually have to be below the power factor number.

The second difference is what determines whether or not the average is likely to equal or exceed the PF is not the standard deviation I used in post 14 for the rule given there, but rather it is the standard error. Where standard deviation tells you how much to expect individual shots to move around an average value, standard error tells you how much to expect the average itself to move around among different test sets of shots. It is equal to the standard deviation divided by the square root of the sample size. For 3-shot velocity samples, it will be 0.577 times the standard deviation.

Based on the above, here is a table for the two-tries at 3-shot passing averages, assuming you know both your average velocity and the SD for your load. Again, you do best to determine your load's average velocity and SD from a single sample of a larger number of rounds. 30 is recommended. Again, I'd add 10 fps to the result below to allow for chronograph and distance variation.

Code: 
Chance of    Average
Making PF    Velocity
50.00%	   -0.315 SD's
60.00%	   -0.195 SD's
70.00%	   -0.069 SD's
75.00%	   ±0.000 SD's (average right on PF velocity for your bullet weight)
80.00%	   +0.077 SD's
90.00%	   +0.276 SD's
95.00%	   +0.439 SD's
99.00%	   +0.740 SD's
99.90%	   +1.068 SD's
99.99%	   +1.317 SD's
 
So, on my latest loads I noticed that the exterior of the brass was much dirtier after shooting. These were lighter loads, I'm working my way down to minor. 6.6-6.3gr of Acc#7 in .1gr steps. Shot 5 rounds at each level with two pistols. What could cause this?

Also, in the CZ TSO, even at 6.3gr. the av. PF was 132. (130, 135, 132, 132, 135). Am I ok to keep going down? Or should I switch to a different powder? Book forumla started at 6.7 for 125gr. In addition to Acc #7, I have Unique, PowerPistol and TItegroup. I'm trying to get to around 127-128.
 
I do not try for barely making power factor.
Looking at chronograph readings and powder measure accuracy, I am probably at f 130.
Tier 1 club level matches seldom chronograph, shave it as close as you like.
Tier 3 state and regional matches, best have a safety margin.

AA #7 is rather slow for target loads and you will see a lot of variation and soot. Of powders you list, Titegroup is most common in IDPA.
 
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