Garmin Xero vs Magnetospeed Sporter Velocities

[Mark71]

Picked up a Garmin the other day and without boring everyone with the same details posted all over the internet, it is everything everyone says about ease of setup and use.

Out of curiosity I wanted to compare it with my Magnetospeed. In hindsight I should have compared with my LR as well, but lately that thing has been frustrating to say the least in getting it to reliably record shots, so I did not take it to the range.

Based on all the research I did prior to purchasing the Garmin I was expecting a difference somewhere around 1 - 3 fps. So off to the range I went with a 223 and 6.5 CM.

223 Data
I shot two 5 round strings with the 223 using Federal 55 gr bulk ammo.

The first string the Garmin was set up 9" left and 15" back of the muzzle. The Garmin was slower anywhere from 5.1 fps to 7.4 fps with the average being 6.1 fps slower. The average velocity for the Garmin was 3265.1 fps and the Magnetospeed was 3271 fps. ES and SD were very comparable (within about 1 fps of each other).

The second string the Garmin was set up 5" left and 5" back of the muzzle. On this string the Garmin was slower anywhere from 3.5 fps to 6.1 fps with the average being 4.7 fps slower. The average velocity for the Garmin was 3242.7 fps and the Magnetospeed was 3247 fps. Here again ES and SD were very comparable.

6.5CM Data
Due to the larger barrel diameter on the 6.5 I initially struggled with getting velocities from the Magnetospeed but after changing the spacing and the sensitivity I finally got a few shots recorded with both units.

In this test the Garmin was also set up 9" left and 15" back of the muzzle. The Garmin was slower anywhere from 9.6 fps to 11.5 fps with the average being 10.6 fps slower. The average velocity for the Garmin was 2693.8 fps and the Magnetospeed was 2704 fps.

As noted above, the velocity difference between the two units was larger than I expected. I'm wondering if anyone else has done any comparisons like this and had the same experience? Are these differences enough to be concerned about?

 

[rijndael]

I have a lot of data comparing my MS v3 and my Garmin, with 6.5 Creedmoor. They line up really well, the numbers are often spot on.

 

[Mark71]

I have a lot of data comparing my MS v3 and my Garmin, with 6.5 Creedmoor. They line up really well, the numbers are often spot on.

Based on my research that's what I was expecting to see...wondering if something isn't quite right with mine...

 

[Tommie]

The real question is which one is reading incorrectly.

 

[Krogen]

A Magnetospeed measures muzzle velocity pretty well. After all, it's hanging on the muzzle. Doppler RADAR chronographs measure velocity downrange "somewhere." They may back calculate muzzle velocity. I don't think we really know exactly where they're measuring it. But that could account for slower velocities. At least with the old optical chronographs, we knew where they measured velocity - because we set them up there.

 

[Mark71]

The real question is which one is reading incorrectly.

I agree. Meant to put that comment in my original post. Even though there's a difference I have no baseline or no way to confirm that one is correct and one isn't.

 

[DocUSMCRetired]

I think your Garmin is too far from the Muzzle. On the display itself it should give you the maximum distances from the muzzle to place it.

 

[Mark71]

A Magnetospeed measures muzzle velocity pretty well. After all, it's hanging on the muzzle. Doppler RADAR chronographs measure velocity downrange "somewhere." They may back calculate muzzle velocity. I don't think we really know exactly where they're measuring it. But that could account for slower velocities. At least with the old optical chronographs, we knew where they measured velocity - because we set them up there.

100% agree with your comments. Who knows what voodoo magic is going on inside that little unit to calculate "muzzle" velocity. I just wasn't expecting a difference in the 6, 8, 10 fps range based on what I researched prior to getting the Garmin.

 

[Mark71]

I think your Garmin is too far from the Muzzle. On the display itself it should give you the maximum distances from the muzzle to place it.

Possibly closer would give tighter velocities when compared to the Magnetospeed. It was never more than 15" from the muzzle which is what Garmin states for placement (5" - 15" to the side and back from the muzzle).

 

[Straightshooter1]

Picked up a Garmin the other day and without boring everyone with the same details posted all over the internet, it is everything everyone says about ease of setup and use.

Out of curiosity I wanted to compare it with my Magnetospeed. In hindsight I should have compared with my LR as well, but lately that thing has been frustrating to say the least in getting it to reliably record shots, so I did not take it to the range.

Based on all the research I did prior to purchasing the Garmin I was expecting a difference somewhere around 1 - 3 fps. So off to the range I went with a 223 and 6.5 CM.

223 Data
I shot two 5 round strings with the 223 using Federal 55 gr bulk ammo.

The first string the Garmin was set up 9" left and 15" back of the muzzle. The Garmin was slower anywhere from 5.1 fps to 7.4 fps with the average being 6.1 fps slower. The average velocity for the Garmin was 3265.1 fps and the Magnetospeed was 3271 fps. ES and SD were very comparable (within about 1 fps of each other).

The second string the Garmin was set up 5" left and 5" back of the muzzle. On this string the Garmin was slower anywhere from 3.5 fps to 6.1 fps with the average being 4.7 fps slower. The average velocity for the Garmin was 3242.7 fps and the Magnetospeed was 3247 fps. Here again ES and SD were very comparable.

6.5CM Data
Due to the larger barrel diameter on the 6.5 I initially struggled with getting velocities from the Magnetospeed but after changing the spacing and the sensitivity I finally got a few shots recorded with both units.

In this test the Garmin was also set up 9" left and 15" back of the muzzle. The Garmin was slower anywhere from 9.6 fps to 11.5 fps with the average being 10.6 fps slower. The average velocity for the Garmin was 2693.8 fps and the Magnetospeed was 2704 fps.

As noted above, the velocity difference between the two units was larger than I expected. I'm wondering if anyone else has done any comparisons like this and had the same experience? Are these differences enough to be concerned about?

When I did my test for Garmin vs MagnetoSpeed V3, I didn't get that much difference and the nearby shooters with their LR's, the velocities were also pretty close to the same as the Garmin. Here's what I got for 10 shots from 6.5 PRC:

 

[CaptainMal]

As stated so well earlier by Krogen, one is measuring velocity right at the muzzle. The other (Garmin) is measuring velocity farther downrange. If is understandable that IF, and the word "IF" is a big deal, they were both exactly correct for their measurement distance from or downrange from the muzzle, the bullet would loose some velocity downrange.

Those saying both measurements were the same imply the Magnetospeed probably reads slower than the Garmin. It would have to be that as a reading at the muzzle has to be faster than at some distance downrange. Bullets don't get faster the farther from the muzzle they go.

Now all this begs another question. What does it matter?

After I got my Garmin I gave the gunsmith, Eric Bostrom, my Magnetospeed. Still have my ProChrony but can't remotely understand why I still kept it.

 

[Tommie]

Now all this begs another question. What does it matter?

In the world most mortals live - nothing.

 

[Mark71]

When I did my test for Garmin vs MagnetoSpeed V3, I didn't get that much difference and the nearby shooters with their LR's, the velocities were also pretty close to the same as the Garmin. Here's what I got for 10 shots from 6.5 PRC:

View attachment 1566808
View attachment 1566810


View attachment 1566811

Thanks for the info! What you were getting for comparison velocities is more along the lines of what I was expecting to see when I did my comparison. Not sure what to make of what I'm getting. Hard to say if it is the Garmin or the Magnetospeed.

 

[Mark71]

As stated so well earlier by Krogen, one is measuring velocity right at the muzzle. The other (Garmin) is measuring velocity farther downrange. If is understandable that IF, and the word "IF" is a big deal, they were both exactly correct for their measurement distance from or downrange from the muzzle, the bullet would loose some velocity downrange.

Those saying both measurements were the same imply the Magnetospeed probably reads slower than the Garmin. It would have to be that as a reading at the muzzle has to be faster than at some distance downrange. Bullets don't get faster the farther from the muzzle they go.

Now all this begs another question. What does it matter?

After I got my Garmin I gave the gunsmith, Eric Bostrom, my Magnetospeed. Still have my ProChrony but can't remotely understand why I still kept it.

I'm beginning to think the same thing...what does it matter. It is basically only a starting point to refine DOPE. Comparing a 10 fps difference in velocity in a ballistic calculator the hold change at 1000 meters is more or less 0.1 MIL. Factor in wind, mirage and ME that 10 fps probably doesn't amount to a hill of beans.

 

[Newhouse]

From the manual: rifle measurement accuracy +/- 0.1 % of the target velocity.

 

[Bill K]

Reading the comments, just makes me stick with my Magneto sporter and be glad it cost me less.
It serves my purpose for FPS just fine.
Overall I probably don't use a Chrony near as much as other do, so maybe the Zero and LR would do them better. I guess it boils down to owner choice.

 

[Mark71]

From the manual: rifle measurement accuracy +/- 0.1 % of the target velocity.

I did see that...just have no way to prove which one is right. LOL

IF the Magnetospeed velocity is accurate the disparity is just over 0.3%, but like I said, no way to know which one is closer to the true velocity.

 

[Mark71]

Reading the comments, just makes me stick with my Magneto sporter and be glad it cost me less.
It serves my purpose for FPS just fine.
Overall I probably don't use a Chrony near as much as other do, so maybe the Zero and LR would do them better. I guess it boils down to owner choice.

I think the MS is a great chrono, but I don't like using it for load development as I have noticed it affects POI depending on the barrel profile. The beauty of a doppler chrono such as the Garmin and LR is you can collect all the nerd data without being concerned that the groups you are seeing on paper are being affected by the MS. I like the MS, I just don't use it for load development.

 

[6.5 forever]

The last comparison I did, the Garmin was 9 fps faster. I can't recall the rifle. It was another shooter at the range wanting to compare his Magneto.

 

[Orr89rocz]

Heres a few with mine. Only shot a few with two rifles
Magnetospeed to garmin - shot 1 2890 - 2886 shot 2 2909- 2902 So fairly close

Other gun shot 1: magneto 3219 to 3206 garmin. Shot 2: magneto 3218 to 3205 garmin, and shot 3: magneto 3223 to garmin 3214. So not bad. Close enough for me