Silver Mountain Electronic question.

[rhovee]

So I have a question about the target system. I had my LabRadar set up at the rifle. Was shooting through the target system at 600. I have shot my 7 Saum load quite a few times and it’s very consistent. The ES at my rifle was 11 with an SD of 4. At the target, it’s claiming that my SD was 17. I am a little suspicious of that. What’s the general consensus with trusting the Info at the target?

 

[Albany Mountain]

That bullet has 600 yards to travel and air, turbulence, moisture, insects, wind direction are all working to slow it down. You don’t have that at the muzzle.

 

[dc.fireman]

So I have a question about the target system. I had my LabRadar set up at the rifle. Was shooting through the target system at 600. I have shot my 7 Saum load quite a few times and it’s very consistent. The ES at my rifle was 11 with an SD of 4. At the target, it’s claiming that my SD was 17. I am a little suspicious of that. What’s the general consensus with trusting the Info at the target?

I've used it for about two years now - it seems consistent. My buddy and I shoot them across 3 different distances at his farm - 300M, 600 yds, and 1k yds. They give different readings at the different distances, but the readings are generally close to each other when the targets are placed side by side. I don't think we've ever had them read exactly the same, but a 2-3 fps difference across the spread.

Next time I'm out there, we'll take screenshots.

 

[rhovee]

That’s good to know. Just hard to imagine that much difference. Someone told me they use the 600 yard data for Bc variance.

 

[Bob3700]

My thought would be that the chrono on the silver mountain system is handicapped by a short sensor length. Would not put a lot of faith on the readings.

 

[NZ_Fclass]

I have found that early morning, overcast, no wind, it can be fairly consistent at 500. Other than that - what the others have said. Before the days of Lab radar, we used to place a chronograph at the target, say 100 or 300 yds. Readings were always better at 100.

 

[daniel.chisholm]

Part of it is that the bullet's speed SD at distance will be larger than its speed SD at the muzzle, for the reasons that Albany Mountain mentions.

Another aspect is that they are different instruments.

The LabRadar is designed to be a precision speed-measuring device, and it is.

The SMT e-target is designed to be a precision shot-position-measing device, and it is. It also happens to display on-target speed, which is a nice-to-have, and a "pretty accurate" number, however it was never designed to be a precision speed-at-the-target device. Whenever peoples' eyes light up and they say "oh good, I can use this to calculate my actual bcs", I try to talk down their expectations of the usefulness of this (bc calculation using muzzle and downrange speed requires extraordinarily accurate speed measurements).

If you want an apples-to-apples comparison, set up your SMT target at 20 or 30 yards. Fire a group into it, measuring the speed of each bullet with both your LabRadar and the SMT. In this way, both systems are measuring essentially the same thing. My prediction is that the SMT's SD will be worse than the LabRadar's, because the LabRadar is a better chrono than the SMT. But I expect the 20-yard-SMT SD will be smaller than the 600/1000-yrd SMT SD.

 

[rhovee]

Thanks for your reply. I will not pay close attention to the SD at the target. Just stick to the lab radar.