Just for fun I calipered some of my new Fiocchi 9mm 115gr FMJ ammo that I just bought just to see what the OAL range was. Interestingly I found that some of the rounds went as high as 1.154” and some as low as 1.148”. So I guess a 6/1000ths spread. Seems like this is quite normal when reading about it. One of the sources I found stated no lower than 1.10 and no greater than 1.65 than all is fine.

Curious as to how accurate this finding is and if it’s an anomaly. I will say I tried multiple boxes though and they all showed similar variations within the range. After the 115gr I wanted to see how another bullet weight measured so I took a some of my 124 grain stuff and it ranged from 1.150 to 1.157 as an added data point.

Are you looking for information specific to Fiocchi or a more general standard?

The SAAMI specification for OAL for 9mm Luger is 1.000 min to 1.169 max. I would think this will vary on bullet type and powders used...

Fiocchi's website indicates the maximum cartridge length is 29.69 mm or 1.17 for their 9mm Luger ammo. You'd have to contact Fiocchi to request their "within specification" range.

Was thinking what’s the acceptable standard deviation in thousandths as it appears that there is about a 6 thousandth spread from low to high from my batches anyway.

I have yet to test other brands of ammo. I have encountered set back ammo before (it had to be quite a few thousandths maybe even a few hundredths shorter than the other rounds) and I was just wondering how many thousandths below the acceptable low end would be considered a set back and what catastrophes were likely at different levels of setback.