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Inconsistencies with Pro Chrono


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Hoping i can get some helpful hints on some weird readings i got yesterday on my Pro Chrono.

I was shooting a 5 inch and a 6 inch 2011 through my Pro Chrono with sky screens attached. The 6 inch gun read fine with no inconsistent readings and i pulled an average average fps of 953 over 10 shots. With the same rounds, I expected the 5 inch to be slightly slower. What I would up with were some shots right were they should have been (900s) but lots of readings of 1200 or higher. Same rounds, same position on the bench. The day was warm and slightly overcast but plenty of sun. Chrono was about 5-6 feet from the bench. With this load all of my shots should have been in the mid-900s. Seems odd I would get so many readings that were 300 fps too high and only from the shorter barreled gun. Ideas??

Thanks, I am new to owning a chrono so am still learning all the tricks of the trade.

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5-6 feet is too close. Set it 10-12 feet from the muzzle and try again. :)

Also, bad batteries can make these things do odd stuff. If moving it back doesn't work change batteries but always keep it at 10-12 feet

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I've been told that having the chrono too close (closer than about 10ft) can lead to false readings due to powder, gasses, etc overtaking the bullet. The 6" gun may have had all of the powder burnt before the bullet left the barrel but some of the powder may have still been burning when the bullet left the 5" barrel.

Of course, these are things I've heard but haven't experienced personally yet. I just got my chrono and have been using it at 15 ft and it has been very consistent load to load and gun to gun.

Last year, though, my ammo clocked quite a bit slower at a section match than ammo from the same box did the day before (same approx temp, gun, etc). The difference was the day before I was "too close" to the chrono; At least that was the explanation offered to me by several folks that I asked.

Sent from my SM-G900P using Tapatalk

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my issues with my pro chrono is that the machine would read the first shot low for some reason after a pause. lets say i shot 5 shots . the first would usually be lower than the next 4. take a little pause to reload mags and it would do it again. i can't figure out why .

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  • 2 weeks later...

I have had zero issues with my Pro Chrono. I have seen quite a bit of negative press but my loads have been with-in 1-2 points of every Level II in the last year. 10 - 12 feet from muzzle is about right. JMHO

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my issues with my pro chrono is that the machine would read the first shot low for some reason after a pause. lets say i shot 5 shots . the first would usually be lower than the next 4. take a little pause to reload mags and it would do it again. i can't figure out why .

Why would you jump to the conclusion that your measuring machine is wrong? Let's see, the first shot. You probably chambered a round, brought the gun up, and pulled the trigger. Powder will be distributed differently in the case than it will on subsequent automatically chambered rounds. Try holding gun muzzle up or down and bringing sights up the same way before every shot. If the first shot is from a cold barrel and the next four are not, there's another discrepancy in what you're trying to measure. That should be enough to get you started.

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