Apparently I need a chronograph

[Tim the student]

If your SD is below 12fps..

What makes it 12, as opposed to 15 (or 11)? I don't understand why 12 is the magic number. I understand the concept of SD, and I get that lower is better, I just don't understand where 12 came from. Can someone answer that for me?

What would be acceptable for handgun velocities? .223?

 

[MCMXI]

What makes it 12, as opposed to 15 (or 11)? I don't understand why 12 is the magic number.

It isn't so don't focus on one number. It's ludicrous to assign one value to SD given the velocity range of ammunition. Take two extremes, an 800 fps pistol cartridge compared to a 3,000 fps rifle cartridge. The desired SD won't be the same for both. Also, don't become a slave to SD. Look at the target below comparing my reloads, Federal Gold Medal Match and American Eagle ammunition. Now look at the velocity data. American Eagle had the lowest standard deviation but is it the "best" load for my rifle? Hardly!!

 

[Robert Wilson]

A chronograph should not be used to decide if pressure is safe or unsafe but you probably already knew that.

Why do you say that?

 

[Tim the student]

Thanks 1858.