Using new chrono for first time, question...

[Scuba2do]

I recently got a digital pro chromo and tried it for the first time today. We checked the speed on some 9mm HP, 45acp HP. I tried the chrono on Sig scorpion 1911 and a Colt gold cup 1911 . The rounds were very consistent at around 920 ft/sec with the Sig and around 900 ft/sec with the Colt. Didn't really know why there would be a difference between the two firearms, guess it must be the barrel. Any thoughts? Interesting observation. We were using AA#7, 10 grains, 230 grain xtreme HP bullet, starline brass. I was very happy with the narrow standard error of deviation around 15 ft/sec. We were getting about 1.5 inch spread shooting. Pretty happy with the overall results and the chrono.

 

[TAROMAN]

Every gun, even identical models, is a story unto itself.
What you observed is totally normal.
Your data look very good.
Now for accuracy tests.

Sent from my LG-D800 using Tapatalk

 

[Rule3]

What Taroman said above^^

Heck, try the same loads in the same gun on a different day or early or late in the day and things will vary.

Take a good sample of at least 10 rounds, Keep the Chrono 10 feet or so from the muzzle.

 

[retired_diver]

What rule3 said and don't let anyone else shoot at it or borrow it. ie if a bullet hits it, it is dead

 

[fredj338]

All gun bbls are diff, even with gun of the same make. Each time a tool cuts steel, it wears a fraction, this translates to the bbl. So you will rarely see any two guns give identical vel. I have 5 diff 4" 357mags, all give diff vel. On is so slow, my 2 1/2" matches it's vel. Yep, a chrono is an eye opening tool to the reloader.

 

[Scuba2do]

The 9mm loads were done using 4.8 grains of Unique, 124 grain HP xtreme, starling brass. We got consistent speeds of around 1045 plus or minus 20 ft/second. Only used Beretta 92FS1A. Looking back I don't know how we reloaded without one of these. I think the biggest thing it does, it reassures the QC of the rounds, makes us be more precise. Thanks for the explanations guys.

 

[Nevada Ed]

Normally the more muzzle blast, the farther you should set up to keep the readings from getting upset.

Welcome to the world of numbers............added to your shooting fun. You will be amazed at what you will discover in the months ahead.