OzFclass

RDavies wrote:

Norm wrote:With the Magneto Speed device. Due to the way it works, I think you need to take the Hysteresis effect into account when recording strings of shots..

Hysterisis effect, Doh, here is another shooting term I don't have a clue about.
Hang on , no, maybe I can use it as an excuse. yep, I had 5 Xs in a row, then the old Hysterisis came and I got a 5 at 3 oclock.

Rod,
My non medical knowledge suggests a bucket of cold water thrown over the patients head will help in cases like this.
Mike.

Mike, only too pleased to contribute to evidence based information, and happy to be screwed over if I make a blue; but like all of us I enjoy the banter and ribbing in the spirit it is intended. Mate we all bleed, and I’m bleeding that my brain ticks over too slowly on the mound and would love to be part of the action these guys are in. Long term memory, analysis and synthesis still viable in the longer timeframe.

Norm, you cryptic fellow, results depend on a past history in order to predict the future. Forrest Gump’s words, “Stupid is as stupid does” is my favourite quote.

It makes little sense to me too why guys or gals would hang an extra weight off their barrel like a Magnetospeed and expect the same harmonic tune with it off.

williada wrote:
It makes little sense to me too why guys or gals would hang an extra weight off their barrel like a Magnetospeed and expect the same harmonic tune with it off.

Precisely the reason I won't use one.

Norm wrote:With the Magneto Speed device. Due to the way it works, I think you need to take the Hysteresis effect into account when recording strings of shots.
The first shot should be discounted and the following shots should be at an even time interval, without the time interval being too long.
I find I get better results when this is done.

I am a bit like Rod. Never, ever heard of that word before.
At first I thought Norm was just taking the piss out of everybody........but NO : https://www.nde-ed.org/EducationResourc ... isLoop.htm

Me thinks this might partly explain those odd occurrences where the MagnetoSpeed will make you raise your eyebrows where you might end up with say a 20-40 fps ES over 12 shots, but it will show two identical velocities for two of the twelve.
Bloody hell..............................Halloran, get me that full bucket !

Shit! Good work Tony, and good work Norm. Send some water down south. Norm, you weren't taking the piss but were on a mission of education.

williada wrote:Mike, only too pleased to contribute to evidence based information, and happy to be screwed over if I make a blue; but like all of us I enjoy the banter and ribbing in the spirit it is intended. Mate we all bleed, and I’m bleeding that my brain ticks over too slowly on the mound and would love to be part of the action these guys are in. Long term memory, analysis and synthesis still viable in the longer timeframe.

Norm, you cryptic fellow, results depend on a past history in order to predict the future. Forrest Gump’s words, “Stupid is as stupid does” is my favourite quote.

It makes little sense to me too why guys or gals would hang an extra weight off their barrel like a Magnetospeed and expect the same harmonic tune with it off.

Dave I'm sorry but I didn't mean to be cryptic.
My comments had nothing to do with accuracy or barrel harmonics. Its was simply referring to velocity recording issues when using the Magneto Speed device.
I totally agree with what you say about accuracy testing with this device attached. It is useless for that. However I think it is an excellent device for velocity recording when properly understood.
The Magneto speed device is different to a normal chronograph. While a normal chronograph that everyone is familiar with works on light. The Magneto speed device works on magnetism.
Magnetism is a strange creature that not many understand. It has some weird properties.
With the Magneto Speed device, the projectile travelling through a set of magnetic field switches, triggers the thing and results in a speed being recorded. When a metal object travels through a magnetic field it produces a back EMF and current flow, the field becomes larger and will remain so for a period of time. Decaying over time.
Hysteresis is the term given to describe the resulting field properties. This may include, direction (polarity), size, sine wave shape and period of decay that the field will exist for.
On the first shot over the Magneto the field will exist purely from that which is generated from the fixed iron magnets and the battery current to the wire coils. ie its electro magnets. Once this first bullet has passes over the magnets, a larger field will then exist.
This larger field strength will decay over a short period of time until it reduces back to the level that it started at.

So if the second and subsequent shots are fired shortly after the first shot. Then they will be flying through a larger and more sensitive magnetic field than what the first shot did. This I believe results in the second and subsequent velocity recordings being more accurate than the first shot.

So when I use my Magneto Speed device, I delete the first shot in a sequence and use the remaining shots to determine ES and SD.

Thanks Norm, very interesting and informative. I suppose if you are going to use these devices you have got to do the research. Its no good having something if you don't know how to use it effectively. You never stop learning. Mate that word will be old hat soon after its been on everyone's lips for a while. David.

Dave,
Its one of the things I had to learn when I became in charge of one of those big spinning things that keeps the lights burning all over Australia.

williada wrote:...It makes little sense to me too why guys or gals would hang an extra weight off their barrel like a Magnetospeed and expect the same harmonic tune with it off.

Me neither but, what if you were to disconnect the cable and leave the device attached for competitions. Because it is then acting purely as a muzzle weight, it should be allowed. And my guess is that harmonics would not be noticeably changed by removing the cable.

Alan

I won't fire if a fly lands on the end of the barrel

Seriously I only use the Magneto for velocity related tests and nothing more. That weight definately effects the harmonics.

Tony, just have cold showers. Your Russian experience is still lingering I would think.

Cam

My research into the science was quite shallow.
Put it on the barrel.
Shoot
Holy shit it works ! How easy was that !!?

It seems i have accidently stumbled onto the correct methodology : I have always discounted/deleted the first shot, for the simple reason that my cold barrel shot is always 20-50 fps slower

Cameron

Whatever happened to the old Rugby motto that "what goes on tour, stays on tour" ?

Norm wrote:

williada wrote:Mike, only too pleased to contribute to evidence based information, and happy to be screwed over if I make a blue; but like all of us I enjoy the banter and ribbing in the spirit it is intended. Mate we all bleed, and I’m bleeding that my brain ticks over too slowly on the mound and would love to be part of the action these guys are in. Long term memory, analysis and synthesis still viable in the longer timeframe.

Norm, you cryptic fellow, results depend on a past history in order to predict the future. Forrest Gump’s words, “Stupid is as stupid does” is my favourite quote.

It makes little sense to me too why guys or gals would hang an extra weight off their barrel like a Magnetospeed and expect the same harmonic tune with it off.

Dave I'm sorry but I didn't mean to be cryptic.
My comments had nothing to do with accuracy or barrel harmonics. Its was simply referring to velocity recording issues when using the Magneto Speed device.
I totally agree with what you say about accuracy testing with this device attached. It is useless for that. However I think it is an excellent device for velocity recording when properly understood.
The Magneto speed device is different to a normal chronograph. While a normal chronograph that everyone is familiar with works on light. The Magneto speed device works on magnetism.
Magnetism is a strange creature that not many understand. It has some weird properties.
With the Magneto Speed device, the projectile travelling through a set of magnetic field switches, triggers the thing and results in a speed being recorded. When a metal object travels through a magnetic field it produces a back EMF and current flow, the field becomes larger and will remain so for a period of time. Decaying over time.
Hysteresis is the term given to describe the resulting field properties. This may include, direction (polarity), size, sine wave shape and period of decay that the field will exist for.
On the first shot over the Magneto the field will exist purely from that which is generated from the fixed iron magnets and the battery current to the wire coils. ie its electro magnets. Once this first bullet has passes over the magnets, a larger field will then exist.
This larger field strength will decay over a short period of time until it reduces back to the level that it started at.

So if the second and subsequent shots are fired shortly after the first shot. Then they will be flying through a larger and more sensitive magnetic field than what the first shot did. This I believe results in the second and subsequent velocity recordings being more accurate than the first shot.

So when I use my Magneto Speed device, I delete the first shot in a sequence and use the remaining shots to determine ES and SD.

So, what would you suggest is a good time interval to maintain when using a magnetospeed?
I try to space my shots out 30 seconds apart, would you say a closer spacing is better for the magneto speed?

One thing I have considered using the Magnetospeed is a carbon fibre tube attachment to the fore end and avoiding any attachment to the barrel. That would eliminate barrel tuning issues allowing a normal shoot to be conducted.

No doubt people have already done just that.

ANY Weight attached to the muzzle will have some tuning effect.

So, what would you suggest is a good time interval to maintain when using a magnetospeed?
I try to space my shots out 30 seconds apart, would you say a closer spacing is better for the magneto speed?

I think 30 to 45 seconds would be fine. But if you had a long break between shots, then I would treat the next shot value with a bit of suspicion.