My LabRadar works fine at the indoor range.
That's the primary reason I got it.
Everything from short barrelled revolvers to double rifles are easy to chrono.
The only thing it won't do is shot shells.
Those little lead balls don't reflect back enough energy to use.
Flat base bullets return more signal than boat tails.
Large calibers work out to longer range than smaller ones.
The display actually has a little indicator showing how much "confidence" or signal each shot produced.

One main trick I learned is to keep the LabRadar unit itself absolutely still during firing.
I put mine on a tripod and separate it from our shooting stands which are not exactly motionless.
My results got WAY more reliable and I am not dropping shot results any more.
The closer the muzzle is to the unit (and just slightly out in front), the more reliable things get as well.
You will have to play with the settings.
I find the 12" setting works best for me even if the barrel is closer than that.
Sensitivity should be set to 1.
I can't get it to work at all at "2".
That must be for 50 BMG or 20mm!

Let us know how this works out for you!

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NEMO
"Everything 44"