Garmin Xero C1 Pro Chrono showing some interesting MV's this weekend.

[mav]

Took my new Garmin Xero C1 Pro Chronograph to the range Sunday. I wanted to get the actual muzzle velocity for certain ammo out for a couple of rifles. I was somewhat surprised by the results and in each case, MV was low as compared to expected. Looking for some info/validation or if I'm missing something.


Here's the breakdown:

1st rifle
Rifle: custom DPMS LR-308 .308 build with a 20" match barrel.
Ammo: Federal Premium Gold Medal Match 175Grain Sierra Matchking BTHP .308

Average MV over 6 shots (cold): 2472.8, Max 2488.7, Min 2460
Expected (based on box) 2600

I'm assuming barrel length for the Federal box is 24". That much drop off to be expected? Also, looks like the fastest of the 6 shots fired was the first from a cold barrel. The next 3 were each sequentially lower, the 5th and 6th were similar and higher than the 4th, so I assume the barrel had "warmed up" by that point.


2nd rifle
Rifle: HK G36 / SL8 build with an HK 18" barrel
Ammo: Winchester M855 green-tipped 62 grain 5.56

Average MV over 50 shots (cold) 2928, Max: 2974, Min: 2873
Expected: 3000-3050?

I think M855 was tested (and designed for) a 20" barrel. Making an assumption there.


Using the integrated ShotView app, pics below:

Federal Premium Gold Medal Match 175 Grain Sierra Matchking BTHP .308


Winchester M855 Green-tip 62 grain 5.56

 

[mav]

Also goes to show it pays to have accurate data (if indeed this is accurate as I have no reason to think it isn't). I've been using higher MV's in my ballistic calculator than what I actually get. Now I can fine tune the calculations.

For those on the fence, the Garmin was super easy to setup and use. Integrating with my iPhone was simple via bluetooth. Easy to use, compact are both things I like. Glad I picked one up. I've not used other chronos, but the Garmin literally took 1 minute to set up: Power on > New session > Rifle cartridge > Ok, place it to the side and a little behind the muzzle and fire away.

Next time I'll run the 168gr .308 to get those results since I have both 168 and 175gr. Still playing around with the G36 ammo so the green-tip was just for fun. I have a bunch of match ammo to test once I have an optic on it. For now, it's just rocking BUIS.

 

[Broc]

I would trust the chrono over the box. Who knows how it was tested in the factory, the temperature and several other factors.

 

[lukewarm_fuzz]

Ignore the box, trust the Chrono, trust dope more

 

[Mudflap621]

From what I’ve read seems most test barrels are around 24”-26”. I have two of the exact same barrels albeit one is 25” and the other is 26”. Running the same load the 25” is about 15-20 fps slower.

 

[general disorder]

That seems about right. When ammo companies (or any other company for that matter) are putting out their numbers they are under optimal, ideal conditions. Nobody is going to come out and say "buy our stuff. It's not bad." I also ass-u-me that I'm being lied too or the claim is exaggerated.

 

[Mountain]

Hi @mav -

Test barrels are not only longer they are usually bolt action. As others have stated, trust the chrony data over the box.

I typically don't shoot 175's except for sniper competition, but your numbers from a semi auto seem reasonable.

 

[Reeg]

Thanks for the info, I didn't know that Garmin made one. I've been considering a doppler chrono that can handle air rifle as well as powder burner speeds. The Labradar seems too finicky and the FX is way too $$'y. This might be the one.

 

[mav]

Thanks for the info, I didn't know that Garmin made one. I've been considering a doppler chrono that can handle air rifle as well as powder burner speeds. The Labradar seems too finicky and the FX is way too $$'y. This might be the one.

It wasn't cheap. I managed to get $50 off, so $550. I'm willing to pay for (small) size, ease of setup and use, etc. Not easy to find right now as demand seems high.

Assuming it will work with air rifles. You can change the mode to rifle, pistol, bow, etc.

 

[cathouse01]

It wasn't cheap. I managed to get $50 off, so $550. I'm willing to pay for (small) size, ease of setup and use, etc. Not easy to find right now as demand seems high.

Assuming it will work with air rifles. You can change the mode to rifle, pistol, bow, etc.

Looks like the Garmin Xero has Labradar running scared:

labradar-ballistic-velocity-doppler-radar-chronograph

Midway also has them at $499.95.

 

[peterk123]

Any updates from the NES xero users? Still love it? Are your results accurate?

 

[mav]

Still love it. Still super easy to use. Only problem is it has exposed my lack of having an accurate range finder and now I need to spend more money. Using my personal pace count like I used to when land navigating/patrolling doesn’t quite do it when the distances start extending out to 300+ yards.

Seriously, now I have super quick, easy and accurate MV data, I’m missing accurate distances for my ballistic calculator. Love the Garmin though.

 

[peterk123]

Nice! It's going to be my wife's and my birthday present to each other. Just the ease of use appears to make it worth while. I hate setting up my chrono. So much so that I don't use it, and I really need to.

 

[peterk123]

Found one in stock. Psyched to use this thing. No more guessing.

 

[peterk123]

It's here. Too bad it's blowing 35 mph outside. Theis thing looks stupid simple to use. Finally, I can chrono every range session. First, we will use it for DOPE card development. Then it's back to reloading!