New CED 'M2' Chronograph
Reader Richard H. just tested his new CED M2 Chronograph, one of the first units in the country. This is an all-new design with many upgrades over the previous CED Millenium model. Clock speed was boosted to 48 mHz, expanding the measurable velocity range to 7,000 fps. Memory storage has been expanded 500%. You can now have up to 500 speed readings per string (and as many as 500 strings). CED claims: “Expanded digital chip design now gives the CED M2 the ability of reading velocities at much lower light levels. On clear days, this means the ability to chronograph from early morning till almost sunset.” If this claim is true, the CED M2 would definitely out-perform rival PACT and Shooting Chrony designs in marginal light conditions.
We’ve found that, with most chronographs, the biggest problems are confusing controls and keypad sequences that are hard to remember. CED has addressed that with the new machine. The $199.00 CED M2 Chronograph features single function string removal (something we wish the Shooting Chrony had), and the M2 offers “one touch” calculation of the average of the three highest velocities in a string. Another major (and much appreciated) improvement is the addition of a USB interface. That offers simple “plug and play” compatibility with laptops and home PCs. USB connectivity will make it much easier to download Chrono data into the updated CED Data Collector software. For more info, contact Competitive Edge Dynamics, CEDHK.com, (610) 366-9752. Right now the CED M2 is back-ordered, but a new shipment is arriving in 2 weeks and M2s should be available by mid-May at Brownells and MidwayUSA.com.
Richard tells us: “I’ve been frustrated for a long time with my inability to get my extreme spreads below 30-50 fps and have wondered if my bargain-basement Chrony F-1 might be part of the problem. Well, after I got my Denver Instruments MXX-123 last month, the powder scale was no longer a credible culprit, so I went shopping for a new chrono. This is what I found. Initial results (only three 5-shot groups so far) suggest that ES with the CED M2 is only half of what the Chrony measured. In the Chrony’s defense though, it is surprisely good for something that costs less than half as much (also more convenient and more portable).” If anyone in the Sacramento, CA area has an Oehler Chrono, Richard would like to do a 3-way comparision test with the CED, Oehler, and Shooting Chrony. We’d all be interested in the results. Contact Mailbox@6mmBR.com and we’ll put you in touch with Richard.
I read with much interest your recent blog article on the new CED ‘M2′ Chhronograph, and the included comments on chronograph accuracy – interesting because chronographs are the one handloaders’ tool which we cannot check. I encourage you to complete the comparative test between chronographs you mentioned. While it won’t be conclusive, it certainly should be interesting.
A couple of comments on your concern with the extreme spreads from your Shooting Chrony are appropriate. If a chronograph uses a 1 foot screen spacing (common among lower-cost models), and a 1 mHz clock (this is a guess), a 3000 fps projectile takes 1/3000 of a second to cross the screens, the clock counts 333 cycles, and a +/- 1 count error will be 2/333 or 0.6%. This equates to 18 fps and compares with the 0.5% error Shooting Chrony claims in their website. On this basis alone, you should not be especially concerned with the ES values of 30-50 fps you mentioned. They are reasonable compared with instrumental accuracy. If you want better data, drill the pivot rivets out of your Shooting Chrony, lengthen the cable, and increase the screen spacing to 5 or 10 feet for a low-cost accuracy improvement of 5 to 10X.
Better yet, forget about ES altogether – statisticians have already solved the problem. The standard deviation, while not intuitive, is exactly what you want, and given a sufficient sample, will not be affected by measurement errors described above. Your chronograph probably already calculates the SD for you. Use it. Chances are, 95% of your shots will be within 2 SD of the average, or chances are 1 shot in 20 won’t be.
No, I have no association with Shooting Chrony, although I do own one and think that for $55 it was a great bargain. Understand that it’s a tool for the casual user, not a lab instrument, its limitations are exactly as you’ve described, and the work-around is either lengthen the spacing, or just forget ES and use the SD.
The CED M2’s processor has a clock speed of 48 MHz. Which makes its error rate per clock cycle (given a 3000 fps bullet) 0.0125% (0.375 fps), not 0.6%.
The Shooting Chrony chronographs all have a 1 MHz processor, the slowest of any chrono on the market. And if you’ll bother to dig in and read their documentation, you’ll find that the 0.5% error rate they advertise is with a 2000 fps bullet. Which extrapolates to 0.75% at 3000 fps, at which velocity the average error would be 22.5 fps. So good luck with your dreams of hand loading to a single-digit SD when your chrono randomly introduces 20+ fps errors.
If a Shooting Chrony is a bargain worth the money, then I suppose you could say the same for the Ford Pinto. That you are satisfied with yours only can mean either your requirements or your standards are very, very low.