CED M2 consistency

[GregJ]

Not sure if my CED M2 is accurate or not. Unfortunately there is not another one in my area that I can compare it to.

Loads are 45 ACP, mixed headstamp, 4.6gr WST, 230g Zero.

Two days before the VA/MD sectional match my loads chronoed at 722/PF166 and 737/PF 169. Temp was about 70*

At the match they were 775/PF 178. Temp was about 90* and humid. My chrono, as well as the match chronos, were CED M2 with the RF screens. Match chronos were boxed, mine was not.

WST is supposed to be slower when it gets hotter. This is a pretty big difference, so I wonder if I may need to send mine and have it checked out.

[RePete]

you could have had light interference from not being boxed.

The humidity will play as will the temp.

[gng4life]

I have had a CED M2 for several years now and mine has been spot on every single time. I usually chrono a few days before a big match and I'm always +/- 2 PF but most of the time it is within 1 PF. My loads over the past years has been with HS6 in an Open gun.

Did you try using your regular screens? What was the lighting like and weather conditions? Was the bullet weight and if so, what weight was it? How many shots per string were you shooting to get your PF (10 shots per strings or etc.)? What was your SD/ES/AVG?

BTW, I never use a box at home but all the Majors I've been to do.

[RePete]

The reason the chrono coffin (the box) is used, with IR sensors, is that the light is consistant, and only humidity and temperature will be the variable.

I have my own coffin that I use.

[GregJ]

I have had a CED M2 for several years now and mine has been spot on every single time. I usually chrono a few days before a big match and I'm always +/- 2 PF but most of the time it is within 1 PF. My loads over the past years has been with HS6 in an Open gun.

Did you try using your regular screens? What was the lighting like and weather conditions? Was the bullet weight and if so, what weight was it? How many shots per string were you shooting to get your PF (10 shots per strings or etc.)? What was your SD/ES/AVG?

BTW, I never use a box at home but all the Majors I've been to do.

No I did not try using the regular screens. I have used the IR screens exclusively to ensure the round is read, and not have to worry about the light not being right.

When I chronoed with mine, temp was 70* clear and nice. Temp at match chrono was 90* clear and fairly humid.

No I did not weight a bullet. I did basically what is done at the match chrono (sans weighing a bullet), fired a string of 3 rounds, averaged, and calculated PF with a 230 g bullet (not weighed). I did this for 2 strings. Given the delta, I doubt weighing a bullet would have mattered that much.

I'll have to pull the SD/ES/AVG off the CED tonight. But not having that data from the match chrono, not sure what that will show.

[GregJ]

I suppose a better test would be to chrono a string with the screens not in a box, and one with them in a box, and see what the delta is.

[Braxton1]

The IR screens are only supposed to be used in the dark. The sensors (the skyscreens themselves) are no different from the standard "daylight" ones. If there is a bunch of white light coming in from all different angles, the IR will be overpowered and you'll lose consistency.

Try the daylight screens or build a coffin.

A coffin for a single set-up would probably cost $30 or so to build. Mine is a dual and cost me $70, including paint.

[gng4life]

By getting this data now, you can build a baseline off of that. It may not help with the past as much but it will help you in the future. Those strings you mentioned, the 166 and 169, was that 10 shots or 20 shots or what? Also, do you connect your M2 to your computer and pull the data from there or do you just copy it? It has a pretty good size memory so you may want to pull off all the data if you haven't already.

I see you are using Zeros and with my experience with them, they are very close to advertised weight. However, if your bullet is off by 5 grains (225 vs 230), that can vary your PF by 3-4 if your speed is 750. I know your PF was off by 9 PF so I really doubt that was it but it's worth checking.

Like I said, I have never used a coffin with mine and I'm always +/- 2 PF and I shoot a lot of matches with a chrono stage (and all of them use coffins). Therefore, I just don't see the need to have a coffin unless you have some really crappy conditions you are always dealing with outdoors or if you have to chrono inside.

[GregJ]

By getting this data now, you can build a baseline off of that. It may not help with the past as much but it will help you in the future. Those strings you mentioned, the 166 and 169, was that 10 shots or 20 shots or what? Also, do you connect your M2 to your computer and pull the data from there or do you just copy it? It has a pretty good size memory so you may want to pull off all the data if you haven't already.

I see you are using Zeros and with my experience with them, they are very close to advertised weight. However, if your bullet is off by 5 grains (225 vs 230), that can vary your PF by 3-4 if your speed is 750. I know your PF was off by 9 PF so I really doubt that was it but it's worth checking.

Like I said, I have never used a coffin with mine and I'm always +/- 2 PF and I shoot a lot of matches with a chrono stage (and all of them use coffins). Therefore, I just don't see the need to have a coffin unless you have some really crappy conditions you are always dealing with outdoors or if you have to chrono inside.

The 166 and 169 PFs were 3 shot strings each. Just like at a match. No I do not connect my M2 to a computer, I just copy it off, but I do clear all memory before any new testing.

RE bullet weight, maybe. Still, very tough to sample. I may as take one out of the pile waiting to load and weight it to use to calculate the PF of each string.

I may try again on a bright sunny day, and try with the regular screens and with the IR screens.

[GregJ]

Per CED literature:

With incredible accuracy, the Patented Infrared Screen
Set eliminates the need for sunlight when using the CED
Millennium Chronograph system, and gives you the freedom
to record velocities under any lighting condition, or if
you choose, no light at all!

This seems to indicate I should be able to use them in full daylight, or in a box.

[gng4life]

By getting this data now, you can build a baseline off of that. It may not help with the past as much but it will help you in the future. Those strings you mentioned, the 166 and 169, was that 10 shots or 20 shots or what? Also, do you connect your M2 to your computer and pull the data from there or do you just copy it? It has a pretty good size memory so you may want to pull off all the data if you haven't already.

I see you are using Zeros and with my experience with them, they are very close to advertised weight. However, if your bullet is off by 5 grains (225 vs 230), that can vary your PF by 3-4 if your speed is 750. I know your PF was off by 9 PF so I really doubt that was it but it's worth checking.

Like I said, I have never used a coffin with mine and I'm always +/- 2 PF and I shoot a lot of matches with a chrono stage (and all of them use coffins). Therefore, I just don't see the need to have a coffin unless you have some really crappy conditions you are always dealing with outdoors or if you have to chrono inside.

The 166 and 169 PFs were 3 shot strings each. Just like at a match. No I do not connect my M2 to a computer, I just copy it off, but I do clear all memory before any new testing.

RE bullet weight, maybe. Still, very tough to sample. I may as take one out of the pile waiting to load and weight it to use to calculate the PF of each string.

I may try again on a bright sunny day, and try with the regular screens and with the IR screens.

That's a good idea. I have the IR screens but I've never used them. My original intention was to make a coffin and use them for that but I never did. I noticed that all my readings were just about the same as each match I went to so I just didn't see the need to make a box and then carry more crap to the range with me.

Actually, that's exactly the way I do it, I thought I was the only one . I run 3 shot strings and calculate the PF but I do that about 10 to 15 times. I make sure that no one string is ever below 169 (if loading Major) and 129 (if loading Minor). I shoot for averages of 172 (Major) and 132 (Minor) to keep them a good distance away from the minimum. The only difference would my Open gun as it sometimes runs better at a higher PF so that may go up to 176-178.

Good luck and let us know your results.

[basman]

The chrono'd at the VA-MD Section were 3 PF faster then my CED. I chrono'd prior to and after the match.

[Fordfan485]

My ammo from the VA/MD match chrono was 139 pf. Same ammo on my chrono was 131 PF.

Edited June 22, 2015 by Fordfan485

[RePete]

My ammo from the VA/MD match chrono was 139 pf. Same ammo on my chrono was 131 PF.

What were the weather conditions when you chrono'd on yours and when they were chrono'd at the match?

[bret]

At chrono they use actual weight, if you have a bullet that is 180.2 grains with an average velocity of 915 fps it makes power factor.

If the bullet weighs 180.0 grains it will not make power factor.

At IPSC Nationals they didn't weigh a bullet, at USPSA Limited Nationals they did, I barely made power factor, I was at 166, my bullet weighed 180.1 grains.

Heard a case where a guy didn't make power factor after firing all of his chrono ammo,,on his last bullet he has the option, shoot it or weigh it, he weighed it and it was just heavy enough to make power factor.