A few posts ago I mentioned I was buying a new CED-M2 chrono to replace my 23 YO PACT MkIII Timer/Chrono. I was starting to wonder about the accuracy I was getting, considering I had recently been seeing some strange results which seemed to relate to operating voltage and remaining battery power during long sessions. I figured my electronic components might be getting tired, starting to drift, and the technology had probably advanced some in the last few years. I also wanted more features, memory storage and download capability the new models sport. Writing down each shot is time consuming and a big pain to re-enter it all into a spreadsheet later. So I had enough justification to rob Peter to pay Paul.... The CED arrived a couple days ago and after carefully cleaning my PACT sensors and setting up a new tripod for the CED screens, Range day arrived.
Before I switched over to the new equipment I wanted to compare it with the readings I am used to getting from the PACT, so a head to head comparison test was in order. I'm not a statistician but I do have an enquiring mind. I'm also cheap, er... frugal... so I had devised a fairly simple test scheme using .22 ammo for the main test and a string of .380 I had previously chrono'd.
For data collection I had 3 setups to perform.
1st - I positioned the tripod screens side x side at 10' from the muzzle. I shot 3 strings thru each chrono.
2nd - I aligned the 2 tripods one in front of the other so I could record a single shot going thru both sets of screens and capture the fps on both units. The second start screen was 6" behind the front's stop screen (12.5' from the muzzle).
3rd - I kept the same setup as #2 but reversed the units position for later averaging.
For setup # 1 I shot 2 brands of ammo, Remington Golden 36gr HP and Blazer 40gr LRN. The rest of the testing was with Blazer since I shot up all of the Remington (good riddance). I didn't use a target since all I was interested in was the velocity, but I still took about 1 or 2 seconds between each shot. and I still had to write down all the data for the PACT, and while I was at it I did the same for the CED in case I fat fingered something and accidentally erased the memory, which also took time.. Altogether I spent 2 1/2 hours shooting 120 rounds. It was a beautiful clear sunny day, not a cloud in the sky. About noon when I started shooting and 2:30 when I packed up. Sun was to my right about 60deg angle.
The CED was pretty easy to get used to. The main thing to remember is to press the STOrage button after each string to commit it to memory or else any additional shots will be added to the end of the current string. This could be a problem when comparing different loads or when shooting different calibers. The CED also has a voice feature that will call out the shot velocity. I turned it off as it was not all that clear and I found it to be distracting.
Everything was going along like clockwork and toward the end I decided to test some .380 I brought along. Unexpectedly I got the strangest readings. While my PACT was reporting velocities of 900 fps the CED was showing speed around 260 !!! My first thought was that maybe I was getting a muzzle blast reading so I stepped back about 5'.... same thing so I stepped back to 20' from the screen... another low reading! I tried repositioning the screens to the sun but that didn't help either. I noticed the CED screen had some codes I didn't recall seeing while shooting 22... it said "10x .6 M" Hmmm I'll figure this out later so I go back to the 10' line and finish the shots, reverse the screen positions and do another string, pack up and go home.
The next step was to install the CED import software so I could upload all my data to Excel. First attempt produced an error - turns out I had to install with an admin account in order to properly register some components with XP. They fail to mention that in the manual but I eventually got it working and it does easily import everything into Excel, just as I wanted. Attached is an example upload into Excel...
While trying to figure out what the screen codes meant and how to salvage the .380 velocities, all I could find in the manual was one statement under the display section that said...
All velocities recorded below 1000 fps will be displayed in (10X decimeters) to the tenth position. (ie: 998.5) All velocities 1000 fps or greater will be displayed rounded to the nearest whole number"
Huh, automatically... decimeter... Well to make a long story longer... It might have changed modes on its own but String # 8 was the one that started this nonsense. That is also the # on the dual function keyboard button to switch between Feet & Meters. I recalled other times when I pressed a key to store a particular string # and instead toggled the "other" function that key is used for. So that explained the 10X and the M display- I was getting my velocity in meters after I fumbled the 8 key. Once I switched the mode back to feet the readings were closer to what the PACT had recorded. The manual doesn't explain this very well and I still don't know what the .6 indicates.
Now for the results... but first I had to do some calculations and conversions to normalize the data a little. Recall that for several of the readings, one chrono was 10' from the muzzle while the other was 12.5', then they flipped position. Also there were a couple shots I recorded while at 15' & 20' away from the 1st start screen. To add to that, I wanted to compare the 10' readings with calculated Muzzle Velocity. Last I also wanted, where possible, to add the similar 10 shot strings together into a 20 shot group for better averaging. To do all this I used an exterior ballistics calculator set to 1' intervals. I had to find the BC of all the bullets used but it didn't take very long at all. I entered a MV until the 10' or 12.5' reading was the same as mine then I used that as the MV for my string. To speed things up I decided to use the shot strings' Average velocity as recorded and convert that to a 10' velocity instead of converting each shot individually. After I had each Avg. FPS corrected for 10' from the muzzle, I calculated what the corresponding MV would be. I compared the two and saw the variation was fairly consistent across all strings. I then paired up the corresponding 10 shot strings and added them together into a 20 shot string and did the MV conversions again. The 10 shot & 20 shot results were very similar.
The bottom line.. the CED averaged about 1-1/2% slower than the PACT, in all strings, with most velocities around 10 to 15 fps slower. An interesting result occurred when comparing the two in-line/position-swap strings.
I took the 10 shots for the PACT when it was in front (at 10') and added to that the 10 shots when it was in the rear at (12.5') This gave an 11' average. I did the same with the CED results. I had enough to produce a second set of 20 shots for each. Using the recorded velocities without any adjustments, both of the PACT strings were the same at 1073 fps and the CED were only 1 fps apart at 1058 & 1059 fps.
So there you have it, the two units seem to be very close to each other. I have no idea if the CED is really slower or the PACT faster but it probably doesn't matter when they are this close, maybe I can just add more powder to make up the difference. (just joking)
I also checked one more thing, I started out with two new 9v batteries that measured 9.67v each. After 2-1/2 hours of use the PACT battery measured 8.76v while the CED showed 8.49v. Now that was a surprise as I expected the new electronics to draw way less power than the older technology but it sure doesn't look that way. Even if it does use as many batteries, I only hope it holds true velocity readings right up to the power off point instead of increasing fps like the old PACT does. at least now I have a backup.
Before I switched over to the new equipment I wanted to compare it with the readings I am used to getting from the PACT, so a head to head comparison test was in order. I'm not a statistician but I do have an enquiring mind. I'm also cheap, er... frugal... so I had devised a fairly simple test scheme using .22 ammo for the main test and a string of .380 I had previously chrono'd.
For data collection I had 3 setups to perform.
1st - I positioned the tripod screens side x side at 10' from the muzzle. I shot 3 strings thru each chrono.
2nd - I aligned the 2 tripods one in front of the other so I could record a single shot going thru both sets of screens and capture the fps on both units. The second start screen was 6" behind the front's stop screen (12.5' from the muzzle).
3rd - I kept the same setup as #2 but reversed the units position for later averaging.
For setup # 1 I shot 2 brands of ammo, Remington Golden 36gr HP and Blazer 40gr LRN. The rest of the testing was with Blazer since I shot up all of the Remington (good riddance). I didn't use a target since all I was interested in was the velocity, but I still took about 1 or 2 seconds between each shot. and I still had to write down all the data for the PACT, and while I was at it I did the same for the CED in case I fat fingered something and accidentally erased the memory, which also took time.. Altogether I spent 2 1/2 hours shooting 120 rounds. It was a beautiful clear sunny day, not a cloud in the sky. About noon when I started shooting and 2:30 when I packed up. Sun was to my right about 60deg angle.
The CED was pretty easy to get used to. The main thing to remember is to press the STOrage button after each string to commit it to memory or else any additional shots will be added to the end of the current string. This could be a problem when comparing different loads or when shooting different calibers. The CED also has a voice feature that will call out the shot velocity. I turned it off as it was not all that clear and I found it to be distracting.
Everything was going along like clockwork and toward the end I decided to test some .380 I brought along. Unexpectedly I got the strangest readings. While my PACT was reporting velocities of 900 fps the CED was showing speed around 260 !!! My first thought was that maybe I was getting a muzzle blast reading so I stepped back about 5'.... same thing so I stepped back to 20' from the screen... another low reading! I tried repositioning the screens to the sun but that didn't help either. I noticed the CED screen had some codes I didn't recall seeing while shooting 22... it said "10x .6 M" Hmmm I'll figure this out later so I go back to the 10' line and finish the shots, reverse the screen positions and do another string, pack up and go home.
The next step was to install the CED import software so I could upload all my data to Excel. First attempt produced an error - turns out I had to install with an admin account in order to properly register some components with XP. They fail to mention that in the manual but I eventually got it working and it does easily import everything into Excel, just as I wanted. Attached is an example upload into Excel...
While trying to figure out what the screen codes meant and how to salvage the .380 velocities, all I could find in the manual was one statement under the display section that said...
All velocities recorded below 1000 fps will be displayed in (10X decimeters) to the tenth position. (ie: 998.5) All velocities 1000 fps or greater will be displayed rounded to the nearest whole number"
Huh, automatically... decimeter... Well to make a long story longer... It might have changed modes on its own but String # 8 was the one that started this nonsense. That is also the # on the dual function keyboard button to switch between Feet & Meters. I recalled other times when I pressed a key to store a particular string # and instead toggled the "other" function that key is used for. So that explained the 10X and the M display- I was getting my velocity in meters after I fumbled the 8 key. Once I switched the mode back to feet the readings were closer to what the PACT had recorded. The manual doesn't explain this very well and I still don't know what the .6 indicates.
Now for the results... but first I had to do some calculations and conversions to normalize the data a little. Recall that for several of the readings, one chrono was 10' from the muzzle while the other was 12.5', then they flipped position. Also there were a couple shots I recorded while at 15' & 20' away from the 1st start screen. To add to that, I wanted to compare the 10' readings with calculated Muzzle Velocity. Last I also wanted, where possible, to add the similar 10 shot strings together into a 20 shot group for better averaging. To do all this I used an exterior ballistics calculator set to 1' intervals. I had to find the BC of all the bullets used but it didn't take very long at all. I entered a MV until the 10' or 12.5' reading was the same as mine then I used that as the MV for my string. To speed things up I decided to use the shot strings' Average velocity as recorded and convert that to a 10' velocity instead of converting each shot individually. After I had each Avg. FPS corrected for 10' from the muzzle, I calculated what the corresponding MV would be. I compared the two and saw the variation was fairly consistent across all strings. I then paired up the corresponding 10 shot strings and added them together into a 20 shot string and did the MV conversions again. The 10 shot & 20 shot results were very similar.
The bottom line.. the CED averaged about 1-1/2% slower than the PACT, in all strings, with most velocities around 10 to 15 fps slower. An interesting result occurred when comparing the two in-line/position-swap strings.
I took the 10 shots for the PACT when it was in front (at 10') and added to that the 10 shots when it was in the rear at (12.5') This gave an 11' average. I did the same with the CED results. I had enough to produce a second set of 20 shots for each. Using the recorded velocities without any adjustments, both of the PACT strings were the same at 1073 fps and the CED were only 1 fps apart at 1058 & 1059 fps.
So there you have it, the two units seem to be very close to each other. I have no idea if the CED is really slower or the PACT faster but it probably doesn't matter when they are this close, maybe I can just add more powder to make up the difference. (just joking)
I also checked one more thing, I started out with two new 9v batteries that measured 9.67v each. After 2-1/2 hours of use the PACT battery measured 8.76v while the CED showed 8.49v. Now that was a surprise as I expected the new electronics to draw way less power than the older technology but it sure doesn't look that way. Even if it does use as many batteries, I only hope it holds true velocity readings right up to the power off point instead of increasing fps like the old PACT does. at least now I have a backup.
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