Precision Rifle Gear Garmin Xero reading high

Call Garmin

How are you confirming it's reading high?

Jefe's Dope said:

How are you confirming it's reading high?

Click to expand...

This.

That sounds like normal rifle variance if it's just difference to factory ammo spec.

Jefe's Dope said:

How are you confirming it's reading high?

Click to expand...

I'm curious as well. Looking to nab one here pretty soon

Environmental changes over the days?

Jcarpenter223 said:

I'm curious as well. Looking to nab one here pretty soon

Click to expand...

Get it from Brownells. That return policy is awesome.

Mine consistently runs about 0.1% to 0.2% low compared to my Magneto Speed when tested at velocities from about 1050 - 2950 FPS. No idea which one is "right", but the variance remarkably low.

100fps higher reading than a Magnetospeed would certainly indicate an issue with one or the other. The 1000 yard impacts would verify which one (which it sounds like you must have). Time to call Garmin if that’s the case because that’s way out of spec.

vh20 said:

100fps higher reading than a Magnetospeed would certainly indicate an issue with one or the other. The 1000 yard impacts would verify which one (which it sounds like you must have). Time to call Garmin if that’s the case because that’s way out of spec.

Click to expand...

This. Chrono data is just an idea for me, then I'll verify at distance

I know two guys I shoot with having similar issues. I believe their variances are around 60-90fps 4 or 5 shots in a string of 10. I consider both of them to be good methodical reloaders.

I have noticed some variance of 60-70fps but only 1-2 shots of a 10 shot string and usually it’s my first 10 shots of the day so thats not enough for me to call it an issue with the unit.

I know you spent the money and want 100% accuracy. However I'd verify the reading with a centerfire group at 6-700 just to see how much (if any) correction was needed. If you're ~ .3 - .4 of a mil off at that range, then you definitely have a 100 FPS reading error. May be a touch more or less depending on cartridge, but anything more than two tenths deserves a little investigation.

I don't ever trust chronographs completely, but they should get you close. My two current cheapos are good for getting me within 30 FPS of trued velocity after I run it at 600 - 650.

Definitely interested in the Garmin myself, so keeping an eye on this thread.

Call me suspicious of amateurs calling into question a measurement instrument's accuracy and precision.

Jcarpenter223 said:

This. Chrono data is just an idea for me, then I'll verify at distance

Click to expand...

Distance tells the truth.

The problem with trying to true your MV at distance is the other variables that can be involved. Not all barrels produce the same BC in a bullet. And bullets have a BC ES and SD as well. If you shoot 20rds onto a 1000yd F Open target I'd take that data as gospel but the ol' 1 to 2 rds in a piece of steel doesn't produce enough statistically significant data. And the biggest variable is the the shooter's ability to maintain a zero. I've seen plenty of guys try to true at distance and F it up. And if you're witness statement is written by a Caldwell color me double-dubious

JR1200W3 said:

The problem with trying to true your MV at distance is the other variables that can be involved. Not all barrels produce the same BC in a bullet. And bullets have a BC ES and SD as well. If you shoot 20rds onto a 1000yd F Open target I'd take that data as gospel but the ol' 1 to 2 rds in a piece of steel doesn't produce enough statistically significant data. And the biggest variable is the the shooter's ability to maintain a zero. I've seen plenty of guys try to true at distance and F it up. And if you're witness statement is written by a Caldwell color me double-dubious

Click to expand...

I believe it difficult to argue with gravity.

5 round groups at minimum, 6-700 for MV, 900-1K again for BC. Works pretty well. If you can't keep a zero at 600, then you can't at 100 either.

Although more than one guy has his own methods of verification, so I'm sure that others exist. I've also found that my single digit SDs translate into .3 MOA/.1mil or less vertical at 6-700.

I find it rare that dudes who are into gathering and truing data points like this are into shooting single rounds for verification. But I know the exceptions exist.

I agree that Caldwell is not to be taken as gospel.

diggler1833 said:

I believe it difficult to argue with gravity.

5 round groups at minimum, 6-700 for MV, 900-1K again for BC. Works pretty well. If you can't keep a zero at 600, then you can't at 100 either.

Although more than one guy has his own methods of verification, so I'm sure that others exist. I've also found that my single digit SDs translate into .3 MOA/.1mil or less vertical at 6-700.

I find it rare that dudes who are into gathering and truing data points like this are into shooting single rounds for verification. But I know the exceptions exist.

I agree that Caldwell is not to be taken as gospel.

Click to expand...

You should listen to Buford Boone talk about testing BCs on an Oehler 88. I used to think truing MV was where it was at. I'd get BCs from Litz. Before he worked at Berger, wrote books, or established AB. When he participated in forums. The more I learned, the more I became aware of errors people made without realizing they were making. It's the classic learning curve. The more you learn, the more you realize how much you don't know. Be careful. If you think you've got it all figured out, you're still in the novice stage.