FX Chronograph Reading Inaccurately with my M3

[rcs9250]

I have a Labradar and the FX chrony. Wanted to do a quick check of the velocity on my Wildcat in the backyard. Turned on phone and FX but it would not sync. Opened battery compartment and there was some battery leakage on one of the spring negative terminals. Cleaned off the corrosion and installed new batteries. Still would not sync. Both times the green LED was on, so I had power. Removed batteries. Center battery was so hot you could only touch it long enough to pull it out and then drop it. Disassembled the case and acid contamination on circuit board. It sat for nearly a year without use. Note to self, remove batteries when not in use. Ordered a Pro Chrono, should be here Friday. Will remove battery when not in use.

 

[nervoustrig]

Alkaline batteries are prone to leaks. Same with “heavy duty” (carbon zinc), though that type would not work well with the FX chronograph because of its high current draw. However in 25 years of using NiMH batteries, I’ve never seen a single one leak.

 

[thomasair]

This is a bit off topic. The downside of the pro chrono is that it operates on a 9v battery and I was constantly forgetting to turn off the unit. Buying a 9v “battery eliminator” solved that problem for me. It’s just a 110v wall plug transformer with a plug on the end that looks like the top of a 9v battery.

 

[rcs9250]

This is a bit off topic. The downside of the pro chrono is that it operates on a 9v battery and I was constantly forgetting to turn off the unit. Buying a 9v “battery eliminator” solved that problem for me. It’s just a 110v wall plug transformer with a plug on the end that looks like the top of a 9v battery.

Exactly what I was planning to do.

 

[carlos_hathcock]

I initially had problems with the FX Pocket Chrono with my M3 also. Tried different settings and returns and it wouldn't read sometimes. A real pain. I now set it about an inch under the barrel and where the muzzle and moderator come together and get good consistent readings. It rarely misses a shot now. I use 20% minimum return setting after trying a bunch.
I also keep an eye on the batteries on the home screen. When I'm at the range I'll turn it off when I'm loading magazines or hanging targets because the thing really drinks the batteries. Energizer Ultimate Lithium batteries last the longest but they are a good bit pricier than Costco/ Kirkland or Duracell.
A buddy uses a pricier traditional style optical chrono and says the FX doesn't read velocities as accurately. That may be true, but as long as I get some reading I can compare it with other readings to find out what the rifle likes and what is consistent then I feel it's useful. I've also gotten five shot strings with all the same velocity and others with 25 FPS variations so I think it's helping find the way forward. It also lets me know when I've gotten all the velocity available from a particular regulator setting no matter if the hammer spring tension goes up.