New Chrony Options

[WP79Vet]

Just spoke with Garmin on the Xero. The support guy said it will not work with “multiple projectiles.” So no-go on saboted bullets (or bullet and wad). I’m thinking a workaround may be to set the radar unit out past where the sabot/wad discards - say 20 feet or so and to the side of the projectile path.

Just spoke with a couple shooters using the new Garmin and shooting with wool wads. Neither that I talked to shoot sabots, others may.

THE WOOL WADS DO NOT AFFECT THE UNITS ACCORDING TO THOSE OWNERS/SHOOTERS.

JUST RECEIVED WORD FROM ANOTHER OWNER/SHOOTER WHO IS SHOOTING SABOTS AND THE UNITS WORK PERFECTLY WITH SABOTS.

Hmmm.... Wonder if the Garmin support guy has enough technical background to understand that wads and sabots are made of non-metallic materials, that they aren't additional bullets, and whether the radio frequencies that the radars use are reflected/scattered by wool or plastics?

I can't imagine that these things operate at radio frequencies which are reflected/scattered by non-metallic materials... they would be utterly swamped by reflection and scattering from vegetation, the ground, butterflies, etc. Because the device is looking for doppler-shifted returns, you might be able to dig the signal out of all that noise by using heterodyne detection techniques.... but why not make life easier by just choosing a wavelength that isn't reflected/scattered by most of what's in the background?

Because my background is in optical physics rather than radio frequency (RF) physics, I don't have a good feeling for how hard it is to choose an RF frequency which isn't reflected/scattered by non-matallic backgrounds, but gives adequate reflection from metallics to pick up tiny bullets. I'm pretty sure, though, that it can be done, because millimeter wavelength RF is what's used for the new generation of airport personnel screening devices which penetrate clothing, luggage, etc. to create images of any weapons that are being carried (along with images of everything else under the clothes....) : A colleague at Pacific Northwest National Laboratory who worked for me for several years was the principal scientist who invented and developed that technology, just before he started working on my projects. Wish I was still in contact with him so I could ask about the radars.

 

[Decay]

Hmmm.... Wonder if the Garmin support guy has enough technical background to understand that wads and sabots are made of non-metallic materials, that they aren't additional bullets, and whether the radio frequencies that the radars use are reflected/scattered by wool or plastics?

I can't imagine that these things operate at radio frequencies which are reflected/scattered by non-metallic materials... they would be utterly swamped by reflection and scattering from vegetation, the ground, butterflies, etc. Because the device is looking for doppler-shifted returns, you might be able to dig the signal out of all that noise by using heterodyne detection techniques.... but why not make life easier by just choosing a wavelength that isn't reflected/scattered by most of what's in the background?

Because my background is in optical physics rather than radio frequency (RF) physics, I don't have a good feeling for how hard it is to choose an RF frequency which isn't reflected/scattered by non-matallic backgrounds, but gives adequate reflection from metallics to pick up tiny bullets. I'm pretty sure, though, that it can be done, because millimeter wavelength RF is what's used for the new generation of airport personnel screening devices which penetrate clothing, luggage, etc. to create images of any weapons that are being carried (along with images of everything else under the clothes....) : A colleague at Pacific Northwest National Laboratory who worked for me for several years was the principal scientist who invented and developed that technology, just before he started working on my projects. Wish I was still in contact with him so I could ask about the radars.

 

[Decay]

WP79Vet; With your background maybe it would be helpful if you spoke to the same guy that ElDiablo spoke to. Maybe he'll refer you to a qualified technical support guy. We've got two considerably different answers now and two professional discussions is a great way to sort out all this for us laymen with no background.

 

[WP79Vet]

WP79Vet; With your background maybe it would be helpful if you spoke to the same guy that ElDiablo spoke to. Maybe he'll refer you to a qualified technical support guy. We've got two considerably different answers now and two professional discussions is a great way to sort out all this for us laymen with no background.

When I get a chance I'll give them a call. Should be in the next day or two.

 

[MrTom]

The video I saw using this new toy showed the unit only a foot or so away from the rifle. muzzle. A sabot and bullet are one unit at that distance. Five feet away I can see the statement saying the sabot won't work with the unit but at a foot there's so miniscule separation at that distance it won't matter.

 

[WP79Vet]

WP79Vet; With your background maybe it would be helpful if you spoke to the same guy that ElDiablo spoke to. Maybe he'll refer you to a qualified technical support guy. We've got two considerably different answers now and two professional discussions is a great way to sort out all this for us laymen with no background.

This morning I contacted Garmin's technical support and spoke to a young fellow named Luke. He is a shooter, and while he doesn't have a technical degree, he studied aerospace engineering for a few years, and works as a liaison between customers and Garmin's engineering department. Garmin engineering doesn't speak directly to customers, but when a customer asks a technical question which the liaison can't answer, the liaison will forward the question to engineering, and then get back to the customer.

Here's a summary of my interactions with Luke:

1. Luke has participated in testing the Garmin chronograph, and personally watched a number of tests where the unit was used to measure the velocity of shotgun slugs as well as bird shot. It worked perfectly for shotgun slugs, but Luke doesn't know whether it was tested on conventional Foster slugs, or more advanced sabot slugs. The unit was able to measure shot velocities about 50% of the time, but did not pick up the shot the other 50% of the time. Luke doesn't know whether the problems experienced in measuring shot velocities was due to the small radar cross sections of individual pieces of shot, or due to interference from the wad.

2. The Garmin chrony DOES NOT produce a curve of velocity versus distance downrange. It collects returns from the projectile out to a distance of about 20 yards, and then uses that data to calculate the muzzle velocity. The user gets a muzzle velocity, and that's it.

3. Luke is going to forward the following questions to engineering, and then get back to me:

a. Will muzzleloader wads or sabots which are made of paper, cotton, wool, or plastic interfere with velocity measurements? Has any testing been done?

b. How does the chrony avoid interference from such wads or sabots? Is there a simple data processing algorithm which chooses the lowest frequency doppler-shifted return and uses that as the basis for the velocity calculation? Does it rely on transparency of typical wool, cotton, paper, or plastic wad and sabot materials to the radio-frequency waves which the chronograph uses?

I'll let you know if/when I receive a reply. My guess is that Garmin engineering will respond... but you never know.

 

[sonny from st. louis]

I would recommend contacting Oehler Research. These people build testing equipment for the big name manufactures and the military. I know some of the testing is done on shot shells and sabot projectiles. That is one thing that sold me on buying an Oehler chronograph plus the tech support is great on both the chronograph and ballistic program. One of the engineers told me that when a new chronograph comes on the market the company buys one and tests it. The Oehler 35P has stayed the same for years because it works. Dr. Oehler line is -- We build our chronographs to work and not to sell. My chronograph has worked fine when it is set up properly. Every shot was recorded as it should. One must be careful where you set it up. NEVER set it up where there is over head obstructions. A cloudy day is the best. The only difference between my chronograph and the ones used at the factories is mine works on a nine volt battery and the factories works on AC power.

Have a GOOD DAY

 

[WP79Vet]

Here's the response I received from Garmin product support:

"Thank you for reaching out to us. Our engineering team echoed a similar sentiment that I did on our call. While most of the technical information relating to radio frequencies is going to be proprietary information, they did say that there should not be an issue for the C1 to pick up shots fired from a muzzle loader, even if there is a sabot present. They agreed that this would be similar to a shotgun slug or other projectile that had a wad behind it.

I also reached out to one of my coworker who shoots muzzleloaders fairly often. He said that he has had a lot of success shooting typical muzzleloader projectiles over the unit, but has not tested sabot's. If you pick up a C1 Chronograph and have any questions or issues please let me know. Thank you for reaching out to us. Have a great day!

Thank you for choosing Garmin

Luke."

As you can see, Garmin isn't willing to share any technical information which might give us confidence that sabots won't interfere with velocity readings. And the way that the following statement is worded - "....should not be an issue for the C1 to pick up shots fired from a muzzle loader, even if there is a sabot present.... " - isn't particularly confidence inspiring: 1) The issue isn't whether the C1 will pick up a ML projectile, it's whether sabots will result in errors; and 2) Use of the wording "should not" gives me the impression that they haven't done any testing with sabot - and maybe that they haven't really thought about it. If they had tested, I would expect them to word the response with something to the effect that they haven't experienced any errors while testing with sabots. During our phone conversation Luke did say that the Garmin chrony had lots of problems when they tried to use it to measure the velocities of shot patterns.... as I think about this, I'd guess that a shot pattern may actually have a greater radar cross section than a single ML bullet - just as radar chaff can have a bigger radar cross section than a fighter jet - so I'm wondering if interference from the wad could actually be the issue they were experiencing.

The small size of the Garmin chrony and the fact that folks who shoot at public ranges don't have to set it up in front of the firing line are attractive features. For me, however, the fact that it doesn't give downrange velocities and the high price are deal killers.

At this point I don't know what to make of concerns about interference from sabots and wads. On one hand, the users referenced by Encore50A (above) don't seem to be having any problems, but on the other hand, Garmin support responses we've received don't inspire much confidence. So... for those who are thinking of buying one, it may be best to wait until we've received more user reports. If anybody who reads this has bought a Garmin radar chrony, please report back after you've sabots, and let us know whether the sabots produced errors.

 

[Decay]

Thank you WP79Vet. I too saw the vagueness of Lukes answer. I hope others that have the Garmin will report with details, and I would thank them for doing so.

 

[ElDiablo]

Here’s a guy on YouTube that demonstrates shooting past the Garmin at various ranges. So it does appear to me that it could certainly be made to work with sabots (IF it had any issues at the muzzle) by placing the unit out at 10 yards or so. And a guy could use it in this way to record downrange velocities.

 

[Kalalau]

Here’s a guy on YouTube that demonstrates shooting past the Garmin at various ranges. So it does appear to me that it could certainly be made to work with sabots (IF it had any issues at the muzzle) by placing the unit out at 10 yards or so. And a guy could use it in this way to record downrange velocities.

That’s a great video!