Different chronograph---different velocity

[copterdrvr]

I have a Caldwell chrono that didnt cost more than around a hundred bucks and i really like it. It came with a cord that connects to my iPhone with a pretty cool app that records all kinds of data.

ANYWAY, my friend has the cheapest model of the Magnetospeed and I did a test to see how close they would be to each other. I already had the Caldwell set up (just put together a Criterion Remage 6 Creedmoor) and was checking some loads, so I stuck the Magnetospeed on the barrel to see what would happen.

I compared the velocities of six rounds and the average difference in velocity showed the Magnetospeed to be 23 fps SLOWER for each recorded round.

Final question-taking into account how each of these units operates, which one would be the most accurate?

 

[Steel head]

Is your Caldwell reading velocities right at the muzzle like the magnetospeed?

The only chronys I generally trust are magnetospeed, Labradar and Oehler 35’s.

 

[copterdrvr]

No, the Caldwell is about 7 feet in front of the muzzle and the Magnetospeed which reads slower is mounted on the barrel.

Do you have any anecdotal evidence that the Caldwell chrono gives inaccurate readings? I'd be curious to hear from folks who actually compared a Magnetospeed to a "high end" chronograph.

 

[Cerwinski]

You should probably move the Caldwell further out. Seven feet is too close. You possibly could get erroneous readings from powder gasses/particles, etc. When I ran an optical I went out about 15 feet or so.

 

[FN-Whitney]

The Magnetospeed V3 is what I use and it has always given me consistent data. Some people complain about a POI shift but I don't care about that, I'm looking for accurate MV. If you allow it to get loose then it will give you some off readings but just keep it tight. As far as accuracy between the sporter and the Caldwell, if it was place tight and with the right height adjustment, that is the MV to use.

 

[Cerwinski]

Oh and BTW when I got my MS I compared velocities between it and the Caldwell. They were within a few FPS of each other consistently. Biggest PITA though was to get the thing aligned and lighting just right. I really like the app they use and wish Magnetospeed would follow suit. I can't get their XFR adapter to work with my Iphone 8 no matter what I try.

 

[copterdrvr]

Thanks for the info-from a technological standpoint I assume the electro optical method would be the simplest way to get an accurate, repeatable reading---cheaply ! ?

I've got a gen 2 little Bastard muzzle brake on the rifle and my thought was that would deflect any ejecta that could cause issues. I've set the Caldwell at 10 feet and got basically the same numbers and it's easy to see the variables as my SD's for the load I'm working with are 4.6 and a 13 spread average-so far.

 

[Steel head]

No, the Caldwell is about 7 feet in front of the muzzle and the Magnetospeed which reads slower is mounted on the barrel.

Do you have any anecdotal evidence that the Caldwell chrono gives inaccurate readings? I'd be curious to hear from folks who actually compared a Magnetospeed to a "high end" chronograph.

7 feet of bullet slow down time between them.
That’s probably 5-10 FPS.

I’ve owned other optical chronys.

Always had issues because perfect light conditions and perfect set up is difficult to achieve.

My magnetospeed and the Labradar I often borrow are within 1-2 FPS.

Before with optical I learned to never trust the ES/Sd because it often didn’t jive with what the bullet told me.

With Labradar and magnetospeed I’m finding I can actually trust what they say to be true down range.

 

[Gunfighter14e2]

My Caldwell shows 50FPS fast in the 2600-2700 FPS range compaired to real world come-up's. However once you get to 3000-3150fps it's dead on with RWD. Like anything else you have to know your gear,....

 

[LawnMM]

Optical chronographs are notoriously inaccurate. That's coming from a guy who still has a CED somewhere. Lighting tends to be inconsistent so you often see higher end units built inside boxes and using infrared lighting.

If you read some of Brian Litzs earlier books he talks about how measured distance to the screens and angle of the screens is extremely important in acquiring accurate readings.

Having said all that, a Magnetospeed is the best Chrono on the market for the type of shooting we do, in my opinion.

I think the Labradors are cool when they work but they're oft reported to be fragile and I've seen them refuse to work at all if it's really windy.

Both are more accurate than the Caldwell, I'd trust the MS reading.

 

[copterdrvr]

I wonder why the Magnetospeed reads 23 fps slower-the unit is my friends -is there anything that equates to "set up" that he could have screwed up when he got his Magnetospeed? I don't know anything about the unit or if it even has anything programable by the user.

Ok,read the newest posts and have one more question-is there anything that the end user can do in a "setup" sense with the Magnetospeed that a user who doesn't really know what he's doing, induce errors-or is it foolproof?

 

[Cerwinski]

I already suggested you try it with the Caldwell farther away. At seven feet you are too close to get an accurate reading of the bullet. You could get higher readings from the gasses/powder particles that are screwing around with the chronograph. Move it out to at least 15 feet and see what it reads.


Edit to add the link to the manual. It recommends 10-15 feet but more may be needed to ensure accurate readings.

Manual

 

[copterdrvr]

Thanks for the info.

Moving on to the Magnetospeed.....

I don't own one, it belongs to my shooting buddy. His is the cheapest version...

Couple of questions;

There's a pretty wide price range between the top end and low end Magnetospeed-I chrono for my PRS rifles, will I miss out on something if I go with the cheapest version
AND
How "programmable" are the Magnetospeed units-in other words, how easy is it for someone who doesn't know what they are doing to screw things up enough to get bad readings. Asking this question because I don't know what was done to the "factory" settings of the unit I used.

 

[Cerwinski]

The main differences involve easy of mounting to different guns. The V3 bayonet is shaped differently to allow for more muzzle devices/suppressors, etc. The main "programming" involves setting the sensitivity level. For instance you may have to increase it a little if you can't get the spacing perfect. Not complicated at all. As far as accuracy I believe they are all equally accurate. The user interface is a little easier with the higher end versions but as I said the main difference is mounting versatility. If you run a lot of large muzzle brakes or suppressors the Sporter version (lowest-end) may not be the best choice for you. If, on the other hand, you shoot mostly thinner-contour plain barrels the Sporter version will suit you just fine. Hope this helps.


Edit to add that if you are worried about the programming being messed with, don't. From my experience if you are getting velocity readings they will be accurate. If you want to check go into the sensitivity setting in the menu. On my V3 the default is "2". The Sporter version is a little different. There is nothing else to mess with in the controls that would affect readings as far as I know. That's the beauty of the Magnetospeed. Very simple and just plain works.

 

[copterdrvr]

Excellent response-much appreciated!

So in other words regarding the adjustment capabilities, it either reads the shot or the sensitivity is increased until it does-correct.? Just curious-what, if anything happens if the sensitivity is turned up too high?


Thanks for the reply!

Copterdrvr

 

[Cerwinski]

If too high or low it will send an error message. Usually it will tell you "too high" or "too low".

 

[copterdrvr]

Excellent-I'll order one today. Still see the need for the Caldwell chrono to get "startup"numbers. I only shoot heavy barreled rifles and the Magnetospeed has impacted EVERY rifle I own. ALL have been impacted by point of impact and the majority have had an impact on group size. It may be minor on some rifles but it still has had an impact.

 

[Cerwinski]

Yes on most of mine it shifts POI UP. What I generally do is find a load that shoots well THEN chronograph it with the MS. Saves a lot of shots that way. You won't be disappointed with it. You should find you don't need the Caldwell at all. I keep mine around for rare times I want to check pistol loads.

 

[Cerwinski]

Oh another thing I noticed. On at least one of my rifles having the MS on actually SHRUNK my groups. Still showed an upwards POI shift but tighter groups. Go figure.

 

[Dthomas3523]

Yes on most of mine it shifts POI UP. What I generally do is find a load that shoots well THEN chronograph it with the MS. Saves a lot of shots that way. You won't be disappointed with it. You should find you don't need the Caldwell at all. I keep mine around for rare times I want to check pistol loads.

For shits and giggles, rotate the bayonet so that it is above the bore. See if it pushes the poi down.

 

[Cerwinski]

Damn I never thought of that. I'll try it next time I use it.

 

[LawnMM]

If you're worried about point of impact shifts during load development (why else would it matter) just get one of the aftermarket mounts that don't use the barrel strap.

 

[Cerwinski]

On a couple of my ARs with the right handguard lengths I just use the pic rail adapter they sell. I even made up one of those Magic Arm mounts for a few guns. I'll just deal with it on my bolt guns as the mounts look really cumbersome to use.

 

[copterdrvr]

 

[copterdrvr]

My stock is an XLR Envy with ARCA rails but I can't find a mount that would work with the Magnetospeed.....

 

[LawnMM]

?

MKM Mount

 

[bschneiderheinze]

Dump the Caldwell

 

[nathan.s.]

If you want to learn more than you ever need to know about chrono’s, Applied Ballistics did a write up about some of the popular options: http://www.appliedballisticsllc.com/Articles/ChronographChapter.pdf

If you don’t want to read through that, here is the highlight showing the relative accuracy of each.

 

[John Glidewell]

Chronograph Accuracy Tips – 15 Practical Tips to Increase Accuracy & Reliability

"No mere gadget, the chronograph is one of the most powerful tools imaginable in load developme...

precisionrifleblog.com

I had a caldwell, still do, but it sits in the garage. I have run the magneto speed and labradar at same time and got same exact numbers. I went with labradar mainly because of the number of rifles I use and load for, just more practical. I made a board that clipped to the back end of the caldwell and I could align it through the scope with a laser bore sight. It worked ok, a lot of effort and it was still not reliable due to light.

right out of the book:

ALL CHRONOGRAPH UNITS HAVE INHERENT UNCERTAINTY WHEN RECORDING VELOCITY MEASUREMENTS. SEVERAL UNCONTROLLABLE VARIABLES CAN AFFECT EACH MEASUREMENT AND CONTRIBUTE TO THIS UNCERTAINTY, INCLUDING SUNLIGHT INTENSITY, SUNLIGHT ORIENTATION, CLOUD COVER, WIND, SHADOWS, AND GROUND REFLECTIVITY OF CEMENT, WATER, OR SNOW, ETC. WHEN COLLECTING DATA, BE SUSPICIOUS OF ANY DATA POINTS THAT HAVE GREATER THAN 4% DIFFERENCE FROM THAT AMMO’S AVERAGE STRING

.2. Position the unit 10 to 15 feet in front of the muzzle of a firearm or if using with a bow, at least one full arrow length in front

I had a piece of tape at the 12.5 foot mark on the cord going to my tablet.

 

[copterdrvr]

I knew this would be the place to get all the answers-thanks guys!

Ordered the Magnetospeed yesterday!

 

[Deleted member 10043]

Isn't the Caldwell accuracy about 1% ??. I know it says .25 but that is a little too realistic. It would have to be perfectly set up with optimal light.

Anyway, no matter what you are using it will change some more when you true it up as well as over the life of the barrel. There are several variables for that too.

I have the sporter MS and a Prochrono from yesteryear. The PC is about 1%. Old secret was put clear packing tape over the sensors to help simulate a cloudy day. Reduces Err to near zero.

 

[Pilotscrappy]

Intrest8ng ....my Caldwell was actually giving me slower speeds than a Labrador.

I was doing load development at the range with my Caldwell when a friendly neighbor shooter offered to let me try his new Labradar.

On this particular string I was shooting my Caldwell was giving me a average of 2755 fps.

The Labradar was clocking in at 2780fps. I was shooting over my chrono while we had the Labradar setup at the same time.

Each shot my Caldwell consistently was reading 20-28 fps SLOWER .......

I'm assuming the Labradar was the accurate chrono as I was running some pretty warm loads at the time.

 

[Deleted member 10043]

That there is the typical 1% accuracy difference I was referring to. It is up to the individual if that is material or not. What I don't check or have seen is the truing error rate when getting ready for shooting to kill or for score. I'm going to go out on a limb and say it gets lost in the true up or down noise variables. That it doesn't matter if you start within 1% or .1% chronograph advertised accuracy for most experienced shooters well under world class levels. Truing that 25 fps shouldn't be any more difficult than starting with a number from an MS or LBR. The only reason I prefer the MS is the set up time.

 

[Kyle92]

Caldwell needs to be 15-20 ft out, and it needs to be leveled, I'd trust the magnetospeed any day over the other.

 

[dntworry]

Just picked up a magneto with the MKM mount should be here in the next few weeks. Hope it lives up to the hype

 

[feelinducky]

I recently upgraded from a chrony to the magneto speed. I had both of them set up to check their differences. I placed the Chrony approx. 10 feet from the muzzle and was getting readings of 130-150fps faster than the magneto speed.

 

[dntworry]

I recently upgraded from a chrony to the magneto speed. I had both of them set up to check their differences. I placed the Chrony approx. 10 feet from the muzzle and was getting readings of 130-150fps faster than the magneto speed.

Did the magneto velocities end up lining up with your actual data a lot better?

 

[feelinducky]

I have not had a chance to figure that out yet. My range is limited to 200m.

 

[308pirate]

Final question-taking into account how each of these units operates, which one would be the most accurate?

Magnetospeed without a doubt

Cheap optical sensor chronographs like yours are a little better than guessing but not by much.

 

[seansmd]

All have errors, I would side with the dope but you mentioned you can't stretch it out to verify.

Did you verify the magneto speed had consistent distance offset along the bayonet?

 

[ufg8rmike]

Man, this is crazy to learn the wide variation in accuracy with chronos. I need to crono a new 6.5 CM to customize a Leupold CDS dial. Anyone from Tampa area or know of a range with an accurate chrono? This is prob only time I’ll ever really need it and don’t want to spend 300 bucks just to get an avg velocity out of 143 grain eld-x hunting round.