A lil' help with load development and evaluation please.......

[Cooter64]

Hello all!
Long time lurker, first time posting.  I apologize in advance for the long winded post......

I have reloaded for rifle for about 10 years, and I have just picked up a Dillon SDB to start reloading for 9mm.  I do not shoot competition, just targets, drills and strive to be a better shooter.  I understand that reloading for rifle vs pistol is like comparing apples vs oranges.  Nonetheless, still fruit.  My questions are when evaluating chrono data of reloads, what values for SD and ES do you consider acceptable.  I have been working up loads using WSF, Fiocchi small pistol primers, Winchester brass, and 124 grain FMJ’s. Working COAL is 1.158”.  

My ladder testing was for (5) rounds in .1 gr increments from 4.7 through 5.3 grains shown below.  Testing was at 7-10 yards.  There we no over-pressure signs through the entire ladder and all primers looked perfect. The most accurate nodes were at 5.0gr (1020 fps), 5.2gr (1074 fps) and 5.3gr (1093 fps) with 5.0gr & 5.3gr being the most accurate.  Groupings were almost identical.

The second ladder test was (10) rounds shot at 5.0gr, 5.2gr and 5.3gr.  Hi/Low outliers removed for a total of (8) rounds counted.

Which load would you pick?  The recoil impulse at 5.0 gr is more like a thump/push and at 5.3 gr it is a little more snappy.  Both are extremely comfortable and manageable. 

Another question I have is, what is the best way to further tune this load?  My options are pretty limited.  I only have Fiocchi small pistol primers so I can’t compare different primers.  I could compare different cases. How much do you play with bullet seating depths?  With rifle, seating depth is great for tuning the load.  I am a little nervous with to do this with the loads I am working with as the cases are quite full now and I would be worried about pressure spikes by seating the bullet deeper. 

Am I over thinking this?  This would not be the first time I have found myself in the rabbit hole.

 

Thanks!
 

[1911flyr]

Don’t overthink. Your most accurate load is more important than the SD. The 5.0 load looks very good and the SD is also very good. By the way, Winchester brass I have found to be the best used brass for accuracy AND SD. The only thing you could possibly try is a shorter OAL of 1.125 to 1.135. The 5.0 load might be slightly higher but not much. That would still be a comfortable load. I am using WSF in all my 9mm loads with great success.

[Farmer]

I generally start .015 off the lands an go from there. My 9 is usually pretty good at that but different bullet shapes sometimes shoot better at .020-.030 off. My 45 seems to prefer .020 or better. I’ve also found that WSF works good in both. 

[superdude]

Since you are not loading for competition where a consistent power factor is useful, you can ignore extreme spread and standard deviation.

 

Testing has shown that there is no correlation between ES/SD and accuracy for the typical handgun at typical handgun distance.

https://americanhandgunner.com/handguns/exclusive-consistent-velocity-accuracy/

 

Serious accuracy testing is done at longer range and with a stable method. You can't tell much from a 5-shot, or even a 10-shot group unless the difference in accuracy is 4-fold plus. Group size will vary considerably even when shooting the exact same ammo. Even then you have to consider the method - offhand, bench, Ransom Rest.

https://www.ssusa.org/articles/2019/9/25/accuracy-testing-shortcomings-of-the-five-shot-group/

https://www.ssusa.org/articles/2021/2/17/accuracy-testing-how-many-shots-in-the-group

 

[GMM50]

I did this EXACT experiment in the 80s.  I plotted not velocity on the y-axis, but group size, since accuracy was my goal.

And i put a 2x scope on my revolver and shot on paper at 25 yards. 

Using a pistol perch, I ran 3 strings of 5 shots and took avg and standard deviation on the group sizes.

 

In every case, group sizes repeatedly increased and then decreased and kept repeating.  Each decrease was less than the previous.

Then I would hit max pressure.  Different bullets, all lead and lubed had different graphs but did not seem to matter.

There was always a good load for each bullet.

 

What you wanted to find was a low group size with a big trough.  This meant small powder charge changes would not affect accuracy (group size)  very much.  I could get 5 shots in one hole but you could see the different shots.  All the holes were touching.

 

Then I trimmed the case length and cleaned out any flash in the primer hole.

I now got one hole.  You could see that several bullets went through that hole but you could not count them.

 

148g Single ended Wad cutter BN 16 (Carrol's Bullets out of business) and 3.4g of W231.

 

[SIGcurious]

On 8/7/2022 at 9:36 AM, superdude said:

Since you are not loading for competition where a consistent power factor is useful, you can ignore extreme spread and standard deviation.

 

Testing has shown that there is no correlation between ES/SD and accuracy for the typical handgun at typical handgun distance.

https://americanhandgunner.com/handguns/exclusive-consistent-velocity-accuracy/

 

Serious accuracy testing is done at longer range and with a stable method. You can't tell much from a 5-shot, or even a 10-shot group unless the difference in accuracy is 4-fold plus. Group size will vary considerably even when shooting the exact same ammo. Even then you have to consider the method - offhand, bench, Ransom Rest.

https://www.ssusa.org/articles/2019/9/25/accuracy-testing-shortcomings-of-the-five-shot-group/

https://www.ssusa.org/articles/2021/2/17/accuracy-testing-how-many-shots-in-the-group

 

 

Great information here.  Thanks.

[Cooter64]

Thank you all for your responses.  I love this site.