Garmin Xero velocity errors???

[Adam Gibbs]

Shot over my Garmin Xero for the first time today. My first set of loads went as expected with velocity about where I imagined it would be(had never chrono'd them before).

My next set of loads shot some weird numbers. 223 77gr SMKs. 23.5gr of Tac. 2.255". I saw velocity numbers from 2490 to 2660 in a 10 shot group. I can't imagine my extreme spread should be that much.

Has anyone with way more rounds overtop of a Garmin notice any errors in velocity? I'm going to load another 20 and see but I'm just curious if I'm doing something wrong here.

 

[HuntHarder]

Mine has been spot on. 0 Extreme spread issues I do not shot over top mine per say tho. I usually have it set to the side of the muzzle

 

[Juan_ID]

I’m sure there’s others that have way more shots over theirs but I have about 500 rounds over mine without any issues like that. Probably 100 of those have been 223 73 eldm loads.

 

[Justin (Raz) Rasmussen]

My next set of loads shot some weird numbers. 223 77gr SMKs. 23.5gr of Tac. 2.255". I saw velocity numbers from 2490 to 2660 in a 10 shot group. I can't imagine my extreme spread should be that much.

Were they all the same brass?

 

[Adam Gibbs]

Were they all the same brass?

All the same brass. Maybe odd, maybe not but my mixed head stamp TMK loads had an extreme spread of 30 something.

 

[Edge]

New Norma 223 brass, Fed 205, AR-Comp, 77 TMK out of Tikka T3 max mag length from a few weeks ago that were shot over my Garmin.

 

[khuber84]

Yeah I've put prob 1k rounds across mine, nothing that ever struck me as, wtf is this? All been good to me. When I first received it, I ran known loads across the garmin and labradar, and everything was within 5fps.

 

[Castle Rock]

I would bet anything it is the ammo

 

[Adam Gibbs]

I'm leaning that way too. I know old school chronos would show bad numbers from time to time, I didn't know if the Garmin sometimes did that. Now I got to figure out why my velocity numbers are so far apart.

 

[Edge]

I'm leaning that way too. I know old school chronos would show bad numbers from time to time, I didn't know if the Garmin sometimes did that. Now I got to figure out why my velocity numbers are so far apart.

My Garmin seems to be spot-on and I use it every range trip now, the only shot it’s missed was when I screwed up. If you can find some AR-COMP, it should tighten up your SDs as it also gives small SDs in 308 Win.

Did you notice velocity rising as you shot your string, chamber temperature causing TAC to increase pressure and velocity?

 

[vonb]

I’ve noticed that with the Lab Radar when I was using the wrong velocity range. E.g. shooting pistol carbines when using handgun velocity range

 

[Adam Gibbs]

My Garmin seems to be spot-on and I use it every range trip now, the only shot it’s missed was when I screwed up. If you can find some AR-COMP, it should tighten up your SDs as it also gives small SDs in 308 Win.

Did you notice velocity rising as you shot your string, chamber temperature causing TAC to increase pressure and velocity?

No it was actually shot 1 and 3 in the 10 shot string that was low. 2479 and 2503. The rest were all about 2630 +/- 30fps. I don't have it in front of me to know the exact numbers.