Odd results with chrono

[midvalleyshooter]

My Buddy and I were at the range this morning practicing shooting. I broke out my ProChrono made by Competition Electronics. I have had it about a year and have used it about six times.

 

All of our loads were giving consistent velocities. Except my Buddies 9mm load. I was using Sport Pistol under either Blue Bullets or Everglades bullets and I got velocities about what I expected. My Buddies 9mm load was 231 under Xtreme bullets and instead of his loads being in the 1,100 FPS range as expected they were 600 FPS or so. We were thinking this was odd as his loads were fine in the past.

 

I then took my carry G19 and alternated his loads with mine in a mag. One of his, one of mine etc. The chrono gave the same as before. Mine around 1,100 FPS and his around 600 FPS. I was firing them and they did not FEEL that much different??? This is one of those things I would not believe if I had not been there doing it.

 

Can anyone offer an explanation? Have you ever seen this before? I'm stumped:)

 

Thanks in advance,

Keith

[Ronemus]

What was the distance from the muzzle to the first screen?  Unburned powder and/or shock waves from high pressure at the muzzle can cause misreads.  The recommended distance to the first screen is 15'.

[midvalleyshooter]

12 hours ago, Ronemus said:

What was the distance from the muzzle to the first screen?  Unburned powder and/or shock waves from high pressure at the muzzle can cause misreads.  The recommended distance to the first screen is 15'.

 

Definitely closer than 15 feet. We were about 6' away. I will try it further out on the next range visit.

[HOGRIDER]

14 hours ago, midvalleyshooter said:

My Buddy and I were at the range this morning practicing shooting. I broke out my ProChrono made by Competition Electronics. I have had it about a year and have used it about six times.

 

All of our loads were giving consistent velocities. Except my Buddies 9mm load. I was using Sport Pistol under either Blue Bullets or Everglades bullets and I got velocities about what I expected. My Buddies 9mm load was 231 under Xtreme bullets and instead of his loads being in the 1,100 FPS range as expected they were 600 FPS or so. We were thinking this was odd as his loads were fine in the past.

 

I then took my carry G19 and alternated his loads with mine in a mag. One of his, one of mine etc. The chrono gave the same as before. Mine around 1,100 FPS and his around 600 FPS. I was firing them and they did not FEEL that much different??? This is one of those things I would not believe if I had not been there doing it.

 

Can anyone offer an explanation? Have you ever seen this before? I'm stumped:)

 

Thanks in advance,

Keith

 

 

From the User Manual:

Quote

On sunny days, shiny, light colored or smooth projectiles may cause reflections which can induce velocity errors. Be sure to use your diffusers on sunny days. However, this may not be enough, by itself, to correct the problem. You can move the chronograph to a location in the field of a shadow cast by a building or an opaque wall. Make sure the sensors have a clear view of the sky but the chronograph itself is within the shadow. An alternate method for this is to use shields taped on the sides of the guide rods to create the shadow. Be sure to use cardboard or something similar that will not cause any problems with ricochets. This will eliminate reflections from direct sunlight, while still assuring that the chronograph has a direct view of the sky. If you are having problems with reflections from shiny bullets or arrows, another remedy you can try is to take a black marker and color your projectiles with it. This will greatly reduce glare and may be needed if you have to use the chronograph in less than ideal lighting conditions.

 

I have found, with my Pro Chrono Digital, that in certain lighting conditions I could get erroneous readings from reflections off of certain bullets.  My fix was to clamp an old pillow case over the diffusers which acts like a "shade tree" directly over the top and/or sides as needed.

 

Also, my SOP is having the center of the Chrono 10' from the muzzle of the pistol.

 

[midvalleyshooter]

On 4/9/2023 at 10:09 AM, HOGRIDER said:

 

 

From the User Manual:

 

I have found, with my Pro Chrono Digital, that in certain lighting conditions I could get erroneous readings from reflections off of certain bullets.  My fix was to clamp an old pillow case over the diffusers which acts like a "shade tree" directly over the top and/or sides as needed.

 

Also, my SOP is having the center of the Chrono 10' from the muzzle of the pistol.

 

Thanks, I will try that.

[motosapiens]

On 4/9/2023 at 11:09 AM, HOGRIDER said:

I have found, with my Pro Chrono Digital, that in certain lighting conditions I could get erroneous readings from reflections off of certain bullets.  My fix was to clamp an old pillow case over the diffusers which acts like a "shade tree" directly over the top and/or sides as needed.

 

Also, my SOP is having the center of the Chrono 10' from the muzzle of the pistol.

 

same here. if the sun is out, I always go under one of the awnings, or fashion a bit of shade from a uspsa target so the sun isn't shining directly on the sensors. Interestingly, I first experienced the problem when using shiny plated xtreme bullets. I haven't actually tested to see if other bullets don't need the extra care, I've just made it SOP to always do it the same; in the shade, and gun 10' from the chrono.