difference between magneto speed and Labradar speeds

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Rebel105
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difference between magneto speed and Labradar speeds

#1 Postby Rebel105 » Sat Oct 28, 2017 7:19 pm

Having just changed from Magneto to Labradar chrony, Just wondering what everyone is experiencing between magneto speeds and labradar speeds. Or, is it in the settings of Labradar. the minimum is 1 metre so, if magneto was 2840 fps what would labradar be???
Last edited by Rebel105 on Sun Oct 29, 2017 6:38 am, edited 1 time in total.

williada
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Re: difference between magneto speed ans Labradar speeds

#2 Postby williada » Sat Oct 28, 2017 7:35 pm

Geoff, there was only a one shot comparison with the magneto speed attached to Albert's rifle beside my Lab Radar at Rosedale a few weeks back and the shot had the same fps reading on both. Certainly not a statistical sample, merely an indicator.

Brad Y
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Re: difference between magneto speed ans Labradar speeds

#3 Postby Brad Y » Sat Oct 28, 2017 8:41 pm

Geoff, I will know more tomorrow as I'm doing some chronograph work in the morning.

Rebel105
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Re: difference between magneto speed and Labradar speeds

#4 Postby Rebel105 » Sun Oct 29, 2017 6:49 am

David,
Interesting to note that I experienced quite a big difference, 40fps. as magneto speed is at muzzle and Labradar is measured at best 1 metre. I wouldn't have thought it was going to be a big difference. Probably a little with different day /temp etc, same batch of powder. The only thing that could upset readings was I used both 180 and 183 gn projectiles without changing the settings for 183's.

6.5x55ai
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Re: difference between magneto speed and Labradar speeds

#5 Postby 6.5x55ai » Sun Oct 29, 2017 7:22 am

I did test Magnetospeed versus LR not so long ago. Used 2 Labradars, unfortunately not at the same time. Results were extremely close. Will dig out the spreadsheet and post it later.
BTW V0 (muzzle velocity) is a calculated figure. The purists could argue that the MS measuring at the muzzle is giving a truer output.
Not sure about the 1 metre figure but most of my shots (284 or 308) are being initially detected at around 6.3 yards out with virtually not much variation in this distance shot to shot which is reassuring.

I always set my LR 120mm to the right of the end of the barrel.

Changing the settings for projectile weight only affects the PF and energy calculation. After forgetting a few times I no longer bother changing the projectile weight value.

6.5x55ai
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Re: difference between magneto speed and Labradar speeds

#6 Postby 6.5x55ai » Sun Oct 29, 2017 8:13 am

LR 1, MS Sporter, Diff
1 2866 2859 7 (Clean Barrel)
2 2911 2906 5
3 2916 2909 7
4 2926 2926 0
5 2921 2916 5


LR 2, MS Sporter, Diff
6 2927 2928 -1
7 2921 2922 -1
8 2917 2917 0

Omark 308, 155gr SMK

Unfortunately I had already sold my V2 and would have liked to do the comparison with that but the Sporter model MS is just as good just less bells and whistles.

We were pretty happy with these results.
Have however seen other tests on the net where the differences have been greater.

Gyro
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Re: difference between magneto speed and Labradar speeds

#7 Postby Gyro » Sun Oct 29, 2017 2:42 pm

A small detail has stuck in my small brain since the day I heard it re velocity testing firearms. It came from a high profile F Class Aussie shooter who came to Trentham about 4 years back and he reckoned the velocity reading is greatly influenced by the way the firearm is held/supported during firing.

Is this true as I have absolutely no idea ? It's just made me think perhaps the Magnetospeed could be better as it would be unaffected by this ?

cheech
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Re: difference between magneto speed and Labradar speeds

#8 Postby cheech » Sun Oct 29, 2017 4:23 pm

We had both going at same time there was maybe 2-4 fps difference and ES & SD nothing in it ,didn't do anything special just turned them on and shoot away

Brad Y
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Re: difference between magneto speed and Labradar speeds

#9 Postby Brad Y » Sun Oct 29, 2017 5:01 pm

Yes shot a string this morning over the ms3 that was measured by labradar last weekend too. Results were very similar in avg velocity and spreads. I think beyond the fact that today was a little cooler and could have had an effect on velocities, there wasn’t anything really noticeable between the two strings.

GSells
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Re: difference between magneto speed and Labradar speeds

#10 Postby GSells » Sun Oct 29, 2017 8:59 pm

Gyro wrote:A small detail has stuck in my small brain since the day I heard it re velocity testing firearms. It came from a high profile F Class Aussie shooter who came to Trentham about 4 years back and he reckoned the velocity reading is greatly influenced by the way the firearm is held/supported during firing.

Is this true as I have absolutely no idea ? It's just made me think perhaps the Magnetospeed could be better as it would be unaffected by this ?


That may have been Cheewy!?? He told me one time he did some testing with a different shooter behind his .284 . The shooter ( who I believe was Vince N ) is of average build and thus smaller than Chewy.
Chewy was saying that get got .20-30 fps more with his bigger frame than Vince . From memory they tested a number of times .
Also preloading into your should from my testing compared to free recoil netted about 20 fps difference? That’s why it’s alway important no to change position during a shoot !

But the above is just my testing and maybe not statistically valid ??

Gyro
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Re: difference between magneto speed and Labradar speeds

#11 Postby Gyro » Mon Oct 30, 2017 4:15 am

Very interesting Graham. If this is true then perhaps it might be as well to get a definitive answer to this one ? Otherwise this casts a rather large shadow on any meaningful discussion here re comparison between different systems, let alone the implications for ES numbers ?

BTW it was Mark F.

6.5x55ai
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Re: difference between magneto speed and Labradar speeds

#12 Postby 6.5x55ai » Mon Oct 30, 2017 5:42 am

Interesting discussion however you have to draw a line in the sand somewhere.
I am happy with what my LR tells me but also let's be realistic here. We are discussing cheap (yes including the LR) consumer grade devices not military grade units costing 10s of 1000s of dollars. The MS and now the LR are for their money streets ahead of optical devices even the Oehler 3P.
I presume tests 4 years old may have been thru optical devices predating LR and possibly MS? Not saying MS and LR will give perfectly accurate results (how can you ever tell, they cannot be checked against traceable standards) but again we are talking cheap instruments here.

And if we decide that ALL cheap chronographs are sus where does that leave us? Load development by estimation, lots of trial and error, many many trips to the range, lots of rounds fired. Although we obviously got by in the days pre chronographs and judgement was usually base on improved centre count.

Brian Litz has a good chapter in Vol 1 of Modern Advancements In Long Range Shooting on modern ballistic instrumentation.

bruce moulds
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Re: difference between magneto speed and Labradar speeds

#13 Postby bruce moulds » Mon Oct 30, 2017 6:40 am

should the hardness of hold affect velocity over the ground, this raises a question re lab radar vs magneto speed.
magneto speed is on the barrel while labradar in on the ground.
would not magneto speed read velocity relative to the barrel, and hence should give velocities relative to the barrel, however the barrel moves?
while lab radar would give a true across the ground speed which might be reduced by barrel movement to the rear and hence potentially variable.
m.s. would be better for speeds including s.d. in a true sense, while l.r would be better in a real sense.
that is of course if the barrel moves to the rear before the bullet has exited the barrel?
how important is all this?
we do not need an absolutely true muzzle velocity, approximate being quite adequate.
what is more important is s.d., and we only need to know that in a relative sense, e.g. the best one.
few people measure enough shots to get a full measure of this.
in the end we are only trying to predict what the target will tell us in order to minimize ammo and barrel costs and time.
and there are other factors that can bring what appears to be a good plan down in a screaming heap.
the advantage of the labradar is that it does not affect barrel harmonics, while its disadvantage is the original cost.
we pay for the target whenever we shoot, chrono or not, and it is the final arbitor.
keep safe,
bruce.
"SUCH IS LIFE" Edward Kelly 11 nov 1880
http://youtu.be/YRaRCCZjdTM

williada
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Re: difference between magneto speed and Labradar speeds

#14 Postby williada » Mon Oct 30, 2017 6:47 pm

Thought I had better clarify some mystery. I found during project Penumbra early 2000 and no doubt others have that with the .308 barrels tested with factory ammunition the average recoil difference with equivalent tight and loose fulcrum points on the butt the reading difference was approximately 20 fps. I also documented this on the sticky regarding rifle recoil in 2014 and addressed the Australian TR Team way back at Bendigo with this fact. Has a lot of implications for tune.

Gyro
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Re: difference between magneto speed and Labradar speeds

#15 Postby Gyro » Tue Oct 31, 2017 3:37 am

As I thought williada : another serious flaw in the 'science' ?


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