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Lane

Anybody have a working RCBS Ammomaster Chronograph?

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I bought one "new" (I thought it was new) quite a long time ago. But it never worked at all. Not even once. 

I called the company and they just gave me some non-sense about how the sun needs to be bright enough; but not too bright. And they couldn't give me any technical details because it was made by another company (in China).

Well. I'm mad. I could have bought a real chrono for that price... 

If anyone has the ability to measure the DC power output from the RCBS head unit on those 1/4" connectors it would be helpful to me. An audio cable, or electric guitar cable and a multimeter are the easy way. Taking the board out is nearly impossible since it's wired to the buttons stuck to the case shell. If you measure on a guitar cable you'll likely find the voltages are backwards (sleeve is positive, tip negative?). I suspect my unit is under voltage by a long shot; even with a new 9V battery.

If I know why mine is broken, I can build a new driver circuit in the short term. Otherwise; this thing is going to be another experimental "guess and check" kind of job. The circuit board inside the RCBS unit looks like a bag of Lays. About 30 chips; all from mid-80s technology. It's horribly overbuilt; and has a mere 10MHz processor.

This thing is not special in any way other than age of technology; but mine never worked at all.

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Thanks for the tip.

I really did think a lot about those magneto speed units; the Sporter version is now about the same price I paid for the useless RCBS (but I'm not sure the cheaper magneto speed option was even available when I bought the RCBS chrono)... At the end of the day; the tech misses the mark on a few things I care about. While I would still like to know what's up with my RCBS unit, I have mostly given up hope. I would happily repurpose the optical triggers (likely photodiodes), if I had an idea what the driving voltage was supposed to be. I assume somewhere in the neighborhood of 27 volts. I presume that is the problem with my board/head unit; boots up, and otherwise acts like it should function...

Since I continue to need something I can actually use; I just ordered and received a Labradar. From what I can tell, it does meet every requirement I had; and is similarly unlikely to get shot. Started reading (inside) the firmware updates they've published online. Even found some internal pictures. While it's just a hair too blurry to be sure; it looks like an NXP brand ARM cortex chip running the show. That helps a lot in terms of making sense of the firmware files. One thing I noticed right off the bat is that the radar frequency settings might be possible to modify in firmware. The version 1.00 firmware is almost completely empty; so there is some kind of base code stored on the unit; assume a full blown RTOS. The take-apart images also show a JTAG port; so that default code might not be off limits. Seems like an extensible platform to say the least. 

Beyond that; I find it strange they use the nomenclature "a : /" file paths for the internal storage (and OS?), and "c : /" paths for the SD card (noticed in the firmware hex as well). That will certainly help in determining what kind of operating system is behind the scenes. Not that I have a lot of NEED to know about that stuff up front, it is interesting from a technology perspective. It's pretty clear they are using a massive array of 24 GHz antennas on the receiver side. Even basic development boards for that kind of 24GHz speed tracking doppler radar are in the same price-range as the complete Labradar unit (so this wouldn't be something I could easily build myself for less).

The Labradar supplied USB cable was dead as a doornail. That freaked me out at first since I was trying to power the unit with it. Swapped that out, and it's been working fine. It sure does eat batteries though. A 5Ah USB charger was down to 80% in about 20 minutes; that's without ever firing the actual radar, just changing settings in the unit. I can see how it would be almost useless with actual AA batteries. You can see in the picture; the cheap USB pack I have securely jams into the plastic body of the Labradar, so I don't have to worry about it laying around, or falling and breaking off the USB connector. They should just create an internal cavity for power packs, and the USB port is just plain awkward where it is currently located. Connected a $30 android tablet over Bluetooth, and it seems to work fine for control and review of data. Actual range report coming soon.

Still interested in knowing the voltage output on the RCBS if anyone has one; but I totally understand that's a niche request that may never be fulfilled. 

Screen Shot 2020-09-26 at 10.18.45 AM.png

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Int-Photos-2503420.pdf

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@Lane, I picked up a MagnetoSpeed this summer, because of the weird stuff (high speeds) with my .308 handloads in the 105*~110* temps.  The MagnetoSpeed is pretty damn nice.  I did the V3 that comes in the hard case, has all the adapters.  Figured it needed to work on many guns.  Very impressed with it's operation, once set up correctly - all you need to do is get that 1/4" space of the rib on that thing below your projectile path out of the muzzle.  So, setup isn't hard - once you get it for that AR15, it's pretty much gonna be the same on another, as long as the barrel profile is close.

Worth the investment to me.  Used it on a few other people's gun the following weekend, gathering data on their hunting loads.  :thumbup:

Edited by 98Z5V

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MagnetoSpeed does seem to be popular. If you only need FPS and ES, and SD it's a great choice. There were only a few minor things that turned me off that option. The change to barrel harmonics (while slight) was a large issue for me. I built a few rifles to look at that particular phenomenon specifically. Also, the relative simplicity of the device leads me to believe the MagnetoSpeed is something I could build myself in an afternoon. In fact; it's little more than an electric guitar pickup and a microcontroller. Probably wouldn't even need to sacrifice a guitar. Just run down to the store and grab some high power magnets, and run some coils up on the lathe. @98Z5V Did you get the V3 or the Sporter model? I've seen you mentioned having one; but not which model. The only further complaint I saw about the MagnetoSpeed; was the lack of time-stamp on data. My understanding is that would be virtually impossible without adding a Real Time Clock (RTC) hardware (chip or circuit board), since most low end microcontrollers don't contain that. The RTC also requires a backup battery (usually a Lithium coin cell).

I messed around with the Labradar briefly around sun down. I must admit, that having already dug into the firmware details bailed me out on a few things. While I still view the unit overall favorably; it absolutely suffers from an engineer's take on what is acceptable in terms of User Experience in the field. There are a number of small things that are likely to be overly confusing for the average user. Every single one of those things could be fixed with a few hours work updating the firmware; something that hasn't happened in nearly two years for the Labradar. Shame.

Full disclosure; it's not hard to learn to work around those nuances once understood. But I could see people getting really pissed off with all the fiddling around that's required to use it effectively.

Nit-picky Technical Issues that would be really confusing if you didn't know why: When using the internal memory for storage; it won't store the full data set, only basic FPS data (so it's a real waste of ammo to use without a functional SD card). That in particular is mentioned in the user manual. There is no useful indication that the SD card is working; and it requires an old style, full size SD card (microSD in adapter didn't work for me, and the manual does say they probably won't). The internal storage also doesn't allow USB data transfer, so you can't even download that FPS only data file. Even using Bluetooth to access internal memory is overly complicated; since you have to view each individual shot record to "save" them to the tablet or phone... Otherwise you only see the shot string container with the number of shots (and none of the individual shot FPS measurements are inside). You still need a pencil and paper...

The bluetooth connection absolutely does time-out regularly. You need to be a real ninja to get in; setup the device, and get back out (or just let the bluetooth time out). Don't expect to keep using the device over bluetooth after initial setup, and maybe arming. And quite frankly, you kind of need to use the bluetooth interface for setup of certain extreme configurations. For one test, I had to enter a projectile weight of 6,083.8 grains; having to do that from the front panel of the lab radar with Up and Down arrows would be a real snooze. The apps over bluetooth also take a long time to do a data transfer every single time you connect. That's not necessary at all. Just poorly planned programming.

Another big UI/UX issue is that you need to setup the preference settings every time you want to use a new projectile weight, or shoot something in a different speed range. The speed ranges have dumb names without any numeric speeds indicated. To measure a can cannon, it has to be set to archery mode. To measure .22LR it has to be set to pistol mode. All that could be fixed very easily be allowing a settings group, or profiles to be stored. Since Labradar device already asks "Are you sure you want to create a new shot string?"; adding those necessary settings would be near zero effort. Then each phone/tablet app has their own special group of settings as well.

From a hardware perspective, the USB port is extremely fragile. They really should add some other kind of power input option that's more robust. Bluetooth specification supports file transfer; so there's no reason to require removing the SD card, or connecting to the USB port to download the .csv datafile. Almost any other storage option besides a full size SD card would be better; those are getting really hard to find these days. A USB type A port would be ideal for a computer type flash drive. Hell; it probably doesn't require any hardware changes besides soldering in an additional physical USB port. There is a ton of empty space inside the Labradar the case. None of the connectors should stick straight out from the unit. It's just asking for breakage.

In terms of Usability. All in all it's a great product that apparently is maintained by people who have absolutely no understanding of user testing, or customer satisfaction. They'd spend a lot less time on support if the product worked in a logical way. I saw one report of a Labradar user sending the unit back for repair to find out their SD card was the fault. How much did that cost? And who paid?

I think almost every review I read said Labradar exceeds manufacturer's specifications in terms of capability; and I've certainly found that to be true on the measurement side (with my limited testing so far). Doppler mode (not triggered by sound) works like crap indoors (inside the house) as it constantly complains about missed shots. But it did work. A spring power BB pistol could be measured more than 50% of the time with the Labradar set to measure out to only 10 feet. It was even able to record some ricochets that didn't stick in to the backstop cardboard (those may have even caused more complaints about missed shots). That is impressive when you consider the manufacturer claims it doesn't work indoors.

Blame Canada. Honestly nobody should have to endure this crap to use a chrono (that otherwise works flawlessly). Full Full Disclosure. I finally got it to work (I think). But I spent more than 24 hours trying to find a fully functional, full size form factor SD card that works in my Labradar. There are multiple fault conditions with SD cards; and none of them inform the user in any useful way (blinking a blue LED is not useful). I have one card that will write empty .CSV shot data files; and crash the Labradar if you try to shoot and record data to the same card. It will never record even a fragment of data from a single shot. Why? That data is certainly already buffered. Hell; the internal memory should store a single shot string at the very least. WTF? Others SD cards are just fully ignored; and the FPS only shot data is stored to internal memory without warning. Those full size SD cards I have work elsewhere, but not in the Labradar; despite meeting the specs explicitly. There are many other fault conditions that could be indicated in some way as well. Failed shots could store partial information at the very least... It's klunky. I have a much longer list, but; fix your firmware @#$%^% *^%%$. Or I'm going to do it for you. :bitchslap:

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Same one I got. Does what I need but I too worry about barrel harmonics. I’m using it for speed info and finding plateaus. I’m still figuring out how to do accuracy testing with it. Right now I find a potential speed node then take it off for the accuracy testing part. This is where a standard chrono or lab radar type would be better cause you wouldn’t need to take it off. Ease of set up and not shooting through a window is nice.

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20 hours ago, Radioactive said:

Same one I got. Does what I need but I too worry about barrel harmonics. I’m using it for speed info and finding plateaus. I’m still figuring out how to do accuracy testing with it. Right now I find a potential speed node then take it off for the accuracy testing part. This is where a standard chrono or lab radar type would be better cause you wouldn’t need to take it off. Ease of set up and not shooting through a window is nice.

I don't care about barrel harmonics with this - I just care about the speed, and I'll take the accuracy results I get.  Speed is the number I need, to further refine my handloads.  After I hit the "needed speed that I need", and make my minimum speed numbers - then I don't need this device for further load development.  THAT is when I start tweaking loads, for accuracy.

Eh, my $0.02 on the whole affair. 

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5 hours ago, 98Z5V said:

I don't care about barrel harmonics with this - I just care about the speed, and I'll take the accuracy results I get.  Speed is the number I need, to further refine my handloads.  After I hit the "needed speed that I need", and make my minimum speed numbers - then I don't need this device for further load development.  THAT is when I start tweaking loads, for accuracy.

Eh, my $0.02 on the whole affair. 

10-4. How do you determine what your min speed is?

that is basically what I’m doing - finding press/ speed flat spot then taking it off and tweaking for best accuracy. I just don’t know what the speed needs to be before I start.

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The discussion about why a MagnetoSpeed is absolutely fine for load development is a valid one; and I welcome it. I've included the patent application for the MagentoSpeed, which does a decent job describing how it technically functions. I've got a solid Labradar update for later; but right off the bat, it looks like the data is the same as what MagnetoSpeed provides. There's apparently nothing magic about the data on the SD card in a Labradar. The only information shown is Ke and PF; but anyone can calculate those with Ke=(1/2m)v^2, and Pf=m*v(and likely formatted for ).

I presume the initial speed is set based on the range at which you wish to use that particular load? And the minimum speed is a requirement based on the distance the projectile needs to stay at a supersonic speed? So something safely away from the transsonic range?

For hunting loads it needs to be above a given speed (at distance) for proper projectile expansion; something which is likely to be a faster speed than simply supersonic?

Just my guesses about the simplicity of a minimum speed requirement. You can always load up in charge until the desired result, or pressure signs. If you can't make the load work, then it's time for a different powder?

Certainly curious to hear thoughts on load development. For clarity: one doesn't need to know the final speed of a load if it hits targets at a speed above the minimum?

MagnetospeedPatentApp.pdf

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I guess there are minimum speeds based on use. I agree it needs to not transit into the sub sonic region to stay stabilized and accurate. Should be easy enough to determine min speed for that at the required distance. I was thinking min speed for best accuracy considering barrel harmonics if you subscribe to that camp. I use it to try to find the highest speed that would allow the barrel to be as accurate as possible then determine if it will stay super sonic at the distance I want to shoot all the while looking for pressure signs which are a little harder to detect in a gas gun compared to a bolt gun. I guess different paths to the same end.

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Another reason for min speed is using less powder. I'm not sure it's a different path to the same end (maybe the same path, and the same end)? 98 will probably stroll in at some point and expound about the minimum speed. I phrased a lot of my assumptions as questions, because I don't know for sure what he meant... And I don't wish to generalize in regards to something that's actually important.

Open for discussion.

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If I recollect most of 98’s loads are running pretty quick. I’m guessing he has a speed number in mind from the get go and when he gets it then he tweaks for accuracy.

I’m far from a long range expert in fact I’m a noob at trying to get there. Been a hunting performance hound in the past but have changed my outlook. Some of the ways I did stuff in the past still hangs around cause I can’t let go. I’m just trying to understand his method and maybe could change the way I do it.

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On 10/3/2020 at 5:54 AM, Radioactive said:

10-4. How do you determine what your min speed is?

 

History.  Knowing these calibers, and what they need to do, in order to be effective.  Example:   Clone some 5.56 Mk262 ammo - that 77gr projectile needs - NEEDS - to leave the muzzle at 2750 fps.  THAT is where the magic happens with that load, from an 18" Mk12.  That's 5.56 loading perfection, right there.  

If it's below that - it's just gonna suck. If it's above 2750fps - that's your magic.  My handloads for that on my 5.56 Mk12 guns are 2780fps - and the thing is a Dragon Slayer...   :lmao::thumbup:

You need to know what the load is capable of, where it's exceptional, and where it sucks.  Once you know that - you load to "beat or match the exceptional" and not have pressure signs, from YOUR gun. 

That is your holy grail, brother...   :hail:

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7 hours ago, 98Z5V said:

History.  Knowing these calibers, and what they need to do, in order to be effective.  Example:   Clone some 5.56 Mk262 ammo - that 77gr projectile needs - NEEDS - to leave the muzzle at 2750 fps.  THAT is where the magic happens with that load, from an 18" Mk12.  That's 5.56 loading perfection, right there.  

If it's below that - it's just gonna suck. If it's above 2750fps - that's your magic.  My handloads for that on my 5.56 Mk12 guns are 2780fps - and the thing is a Dragon Slayer...   :lmao::thumbup:

You need to know what the load is capable of, where it's exceptional, and where it sucks.  Once you know that - you load to "beat or match the exceptional" and not have pressure signs, from YOUR gun. 

That is your holy grail, brother...   :hail:

Gotcha. Thanks for the info and good read. 

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On 10/4/2020 at 10:01 PM, 98Z5V said:

https://www.shootingtimes.com/editorial/special-forces-to-civilians-black-hills-mk-262-mod-1-review/99098

THIS kind of load development is what you want from ALL your handloads...   Regardless of caliber... 

I ended up reading this over a few times to fully digest some of the finer points. There where just a few things it left out in terms of history; and that made me curious. I finally found this quick write up about the MK262 vs. MK262 mod 1 and it helped me fill in the gaps. https://www.ar15.com/ammo-oracle/history/mk262.html

Realized I do have some of the Hornady 75 grain match projectiles; but none of the other options on hand. This listing on targetsports says 2725 FPS for the mod 1 ammo (https://www.targetsportsusa.com/black-hills-5-56mm-mk262-mod-1-ammo-mod-1-c-77-grain-otm-mp460556n9-p-110508.aspx); but 98Z5V says 2750 FPS. And higher... I think I remember reading hints about this in another thread around here. Those numbers are helpful; though I'm curious how close to the limit those are in terms of pressure. Is that 2780 riding a fine line?

Have a few piles of once fired and freshly primed brass that I could get started with. While I'm rather range limited at the moment; I could at least try and hit the FPS number short term.

Haven't killed the Labradar yet; but I did try to flash a custom modified firmware. It didn't take, but I also didn't try to change the version number, or otherwise force it in any way. That will be on my list the moment I see a new firmware update from them. I could try to mod the older update file, and flash that to see if I'm allowed to version swap. That's a decent option to "force" it to take an update if it does allow. Trying not to break it before I get some use out of it.

I won't blame Canada. Quebec is indeed why it's confusing. As I was browsing the firmware binary for the latest update (pre-loaded); I realized it contains a fully french language translation in code. It also contains numerous features not accessable to the end user. There is likely a developer mode that may or may not be easily accessable. I tried booting the unit while holding various buttons; but nothing has changed yet. It does show up as NXP LPC on my computer; which is a brand and chip family. Just need to know exactly which model number still (and I haven't cracked open the case myself). Knowing chip number; I can buy a dev board and simulate the device externally as a means to safely develop updates on my own. Still rather impressed with the Labradar hardware overall; despite some unnecessary shortcomings in user interface.

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49 minutes ago, Lane said:

 I'm curious how close to the limit those are in terms of pressure. Is that 2780 riding a fine line?
 

No pressure signs, at all.  I saw pressure signs after that, though, going up in charge weight, before I hit the next accuracy node.  I stopped there for 2 reasons - wasn't gonna make the next node, and stay safe, AND I hit my target of 2750 or higher.  It's one hell of a great load, but it took time to sort it all out and get there. 

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Sounds good to me. I'll start at the lower FPS number and see what kind of metrics I can hit with powders I have on hand. If the lower powder/cost/chamber pressure node works; the next one up is only going to sacrifice wear and reliability from what I can tell.

Taking my time to work up slow in a number of areas. A shot timer / barrel flex measure unit just got flashed with the lastest firmware. I'm not at all sure how many libraries need an upgrade; but there will be a few more... Even the current software could measure those metrics over a 5-20 shot test with some tweaking. Some of those fresh ideas came from learning about the Labradar; so I've yet to write that new code. I presume updated libraries might also bear fruit in terms of timing issues I was earlier running into. Green numbers are angular measurements; the ones I want most... Shot timer already works; but needs a few updates for display on this new hardware still (long standing bug).

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Making a quick update here; mostly for my own documentation. The shot timer upgrade wasted a ton of my time recently; trying to figure out why the gyro numbers weren't showing up, or recording. I finally got it to sort of work, and set it aside briefly because I didn't want to break it again. Only then did I realize that a few of the newer orange boxes have totally different inertial measurement unit chips inside. That means that code for one; doesn't work to read the other. This is a very minor problem now that I know; the units are otherwise identical, and the rest of my code is entirely portable between them. This is now the 5th official hardware change since I started this project (including my initial breadboard proof of concept shot timer)... It has come a long way since then.

Even with default gyro settings, overloading the CPU with audio recording from the microphone, and drawing display updates; I was able to get readings every 4 milliseconds. Not quite what I need; but turning off the peripherals I don't need will easily be enough. This newer IMU chip also has a much larger buffer; so I'll be able to record 2-4 milliseconds of gyro data at full speed, and then download that from the chip into memory or flash afterwards for processing. The goal here was to be able to graph physical barrel movement from trigger pull, through the projectile exiting the barrel. Worse case scenario is that I need to run a few precisely made reloads with a timing offset to collect a full data set. If I can collect 64 samples in a 2ms time span, I won't worry about that much. But if it drops down near 16 samples; I'll want to collect more data with an offset trigger time as a verification.

Finally out of the weeds on this project. And all the problems started because I was trying to use the hardware I have on hand, round-robin to ensure the internal lithium batteries wouldn't go bad from sitting around too long... I haven't normalized the readings (zeroed X,Y,Z), but the flutter is easily below the published +/- 1% of a degree in angular velocity. Found some newer research that inserts this type of IMU inside of larger projectiles; then recorded data while firing them. That process doesn't seem to work well to look at what the barrel does, given the projectile itself is experiencing such dramatic changes as it accelerates down the pipe.

Those green numbers changing faster than the LCD display can update; and faster than the camera can record are what's special here... Still showing the boot time demo screen; but it already records gyro data to RAM. Initial test measurements on live hardware should be possible in the next week or so easily. Might be worth starting off with subs to allow for a longer data collection window during those early hardware verification tests. Progress.

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