Standard deviation in pistol rounds

[Nmhuntr]

I am new to reloading and have been working on some rounds and then checking them on a Caldwell Chronograph. My SD Is really bad. I am loading 6-10 rounds and measuring my powder with a Franklin digital scale. I do not ensure all of my case lengths are the same but they are all in spec. I am hoping someone can tell me what to tweak so I can get consistent rounds. These are not for competition jut range shooting. Here is what I have:

9mm (SD 23.2-24.4)
Federal case (once fired)
Copper plated 115gr
Titegroup 4.2gr
CCI SPP
COL vary from 1.153 up to 1.16

.380 (SD 36.7)
PMC Case (once fired)
90gr XTP
Titegroup 3.2
CCI SPP
COL .964-.9655

Thanks for sharing your expertise

 

[450shooter]

In my opinion you will never see that SD on the target. As long as they function and shoot fine I wouldn't worry about it.

 

[Nmhuntr]

Thanks
I was wondering if I was concerned about nothing. For rifles I get it but for hand gun target shooting I was thinking that I was probably digging in too much.

 

[K22]

I shot competitive NRA precision (bullseye) for about 30 years. I never seen or heard of any shooters, including master class shooters ever measuring the SD of match pistol loads. In this competition, match caliber pistols are used and to be competitive your pistol / ammo combo should hold an "X" ring at 50 yards which measures about 1.7" in diameter.

My S&W Model 41 and even my Model 17, a target grade revolver, was capable of this with factory target grade rim fire ammunition when tested off a mechanical Ransom Rest. Accurized 45 ACP's routinely held this level of precision with standard target reloads, i.e. Bullseye powder and 185 grade match grade lead bullets.

So I wouldn't concern myself with SD or even measure it even if you were shooting match grade pistols.

 

[Nmhuntr]

I shot competitive NRA precision (bullseye) for about 30 years. I never seen or heard of any shooters, including master class shooters ever measuring the SD of match pistol loads. In this competition, match caliber pistols are used and to be competitive your pistol / ammo combo should hold an "X" ring at 50 yards which measures about 1.7" in diameter.

My S&W Model 41 and even my Model 17, a target grade revolver, was capable of this with factory target grade rim fire ammunition when tested off a mechanical Ransom Rest. Accurized 45 ACP's routinely held this level of precision with standard target reloads, i.e. Bullseye powder and 185 grade match grade lead bullets.

So I wouldn't concern myself with SD or even measure it even if you were shooting match grade pistols.

Thanks a lot. good to get feedback from those of you with experience

 

[lotech]

Few gave any thought to these numbers before the Internet. There's nothing wrong with low numbers, but low numbers indicate consistency, not accuracy. There are many other factors that affect accuracy, so many in fact that SD and ES numbers are far overshadowed by them in most instances.

I pay no attention to the numbers if I'm getting good accuracy during load development and testing. I think SD and ES numbers may have importance for rifle shooting at extended ranges, say more than 500 yards, where all changeable factors must be narrowed down for best accuracy, but I've never tested this. The pros probably know.

 

[RegionRat]

@Nmhuntr , those numbers are about average for the 9mm and okay for almost anything but the pickiest applications. Your 380 numbers are pretty good too. Those can be tricky to reload in general.

The semiauto designs are a little different than some of the rimmed revolver designs in that those revolver cartridges can have heavy roll or taper crimps into cannelures which can tighten the velocity stats. Semiauto designs tend to headspace differently so the two are hard to compare. That said, the more consistent the brass prep and neck tension, the better your stats will run.

When you have more resources at your disposal, try playing with different brands and thicknesses of brass and sizing dies. You will see the effects on the velocity stats. For now, you are doing okay.