FJRider

I too had frustrations using my Chrony (Alpha model). Measurements early in the day or in Winter were always subject to issues... sensitivity to blast was another (I measured the jet one time at 4700 fps! Way too close that time..), perfect alignment with the sensor and the projectile was a must, etc., etc. My solution was to build a four sided box for the Chrony, to which I added the optional LED lights - both front and back are covered with paper (target in front /something like newspaper in the back). Results have been terrific - sunny days, low angle sun, sun in front /back, cloudy days, inside under flourescent lights (a nemesis for many chronographs and common to most indoor ranges), etc, I can measure my loads reliably. The only mistakes /missed measurements are when I am setting up and getting the gun aligned with both sensors (so that the projectile will pass over both) - I have since added reference guides that make this a no-brainer. I also use a blast shield (essentially a baffle with a vertical slit through which you shoot - looks weird but it works very well) for up close distances. I do have to mount the box on a stand now, instead of the tripod I was using, but that is a minor inconvenience. But a new chronograph that alleviates the Shooting Chrony weaknesses is also a great solution - good to hear about the versatility of the ProChrono - this would have saved me a lot of confusion /frustration. Wil keep that in mind for future reference.

Although this thread is a bit old, I'd like to share my experiences with my Chronograph and how I fixed them. I too had varying speed measurements of as much as a 1000+fps or more. Chrono used was an Alpha Shooting Chrony but I think these tips are universal for all. My solution was a number of changes that has resulted in no more issues (at least for me.. YMMV!) 1st: I was too close (under 10 feet), solution was to move out; now I use a commonly recommended 15 feet. Being close allowed the blast gases /particles to reach the chrono before the bullet. 2nd: Lighting was also an issue - at low angles of the sun (common in winter or early/late in the day), the sensors were not seeing the bullet's shadow. My solution was to get the accesory LED lights from Shooting Chrony for the chronograph. Note: flourescent lights are a big no-no's for chronos, their oscillations in brightness confuse the sensors; I noticed that any flourescent lights within 50feet of the chrono could affect it. Lastly, after researching a bit on what other used /did, I decided that isolating the unit from the environment would work best for my uses (both outdoors and indoors) and built a chrono box (a quick Google search will show you lots of pictures) to house the chronograph and the LED lights; box has an integral blast shield (essentially a small hole that you shoot thru to diffuse /reduce any blast gas effects) and a disposable /consumable sun shield on the exit side. You could easily build a blast shield to sit in front of any chrono (just use a small hole, say 3-4in diameter, or a slit, say 2in by 4in) out of a variety of materials (cardboard will work since you are just slowing /diffusing gases, just do not let it get moved around). Good tip for the box is to paint the inside a flat -no gloss at all- black. I recently used the new chrono box setup outdoors in the low angle light of winter (sunlight angle had to be 45deg.. object shadows were completely off to one side) to chrono .223 loads with excellent results -- 71 shots were fired across the chrono and all were measured perfectly fine with no abnormal readings. Now I can focus back on getting those those SD/ES down to size! Cheers!