MagnetoSpeed, How well do they work?

[6BRinNZ]

The MagnetoSpeed affects both POI and group spread with every rifle I've attached it to (.223 and .308). If you're not shooting 100 yd groups in the 0.25 to 0.3 MOA range (or smaller), you may not notice it. But it's definitely there; anything with sufficient mass hanging off the end of a barrel is going to affect the harmonics to some degree, this is simple physics and cannot be debated. If you don't notice a dramatic change in group size, it probably won't be an issue for you. But that doesn't mean it isn't there.

I (and others) posted a series of tests at another shooting forum (SH) on this topic quite some time ago. The best evidence suggests that the shift in POI is due to muzzle blast off the sensor deck. Any type of muzzle brake that diverts expanding gases away from the sensor deck will lessen the POI shift effect proportionally to how much gas is diverted. However, it will not alter how the device affects barrel harmonics, which will be proportional to the mass and position of the device.

Don't get me wrong, I love my MagnetoSpeed and wouldn't be without it. But I do not do load development with it attached. Rather I should say that my velocity rounds and group rounds during load development are done separately. I do not find it ideal in terms of time, effort, and reloading components. But I'm not willing to accept the results of both velocity and group spread with the device attached. YMMV. I'm looking forward to the debut of the LabRadar device, which seems like it may be the best of both worlds as chronographs go.

Out of interest - if you used Eriks' 100 yard approach for powder only (with magneto attached) - would you end up with the same powder node? While its not being argued that the group size is larger does it still reflect the same POI differences between charges and therefore the same powder conclusion is arrived at?

You may not have looked at the targets this way - I'm only curious since you have undertaken more testing.

 

[sbhooper]

I don't understand why anyone would want to test accuracy over a chrono. Get the accuracy figured out and then test the velocity. It doesn't matter if the chrono makes the poi shift. Those should be two different operations in my opinion.

 

[Raythemanroe]

What good is a Chronograph if your not keeping track of the ES while working up a load? I could careless about my velocity otherwise..

If your a tacticool shooter and want numbers to punch in for your ballistic calculator wouldn't a low ES be crucial? If you shoot a velocity through the Chrono and it is 50+ fps different the next shot I would guess that would fudge your come ups.. I guess the OCW guys already know the best charge for a given caliber bullet combo..


Ray

 

[Raythemanroe]

I like my chrono running while I'm observing vertical and keeping the data written down.. I like to work up to pressure signs and usually get more then one node.. Chrono helps with what one will begin seating depth testing.. It also helps determine whether I should try another powder or primer..



Ray

 

[Bert]

As much as I love the magnetospeed I wont use it for load development. I use the ohler. I always shoot across the crony when doing load work. Why not? I guess if you do your load work at 1000 yrds then you don't have a need for a crony. But most of us don't have 1000 yrds in the back yard. Powder and bullets are to expensive not to collect as much data as you can. With all this said just used the magneto again today easy and quick. great product.

 

[Macropod]

I have thought about getting the Magnetospeed, but mounting it on an attachment to the tubegun stock I am using. The idea being there is no weight to upset barrel harmonics and vibration. 8)

Has anyone else tried this?

 

[6BRinNZ]

I actually do look at the data in that way because I am shooting groups/targets with the MagnetoSpeed attached while I'm measuring velocity. I just don't use the MV group spreads for determining optimal charge weight. In general, I would say if everything is working right, they probably wouldn't be off by more than 0.1-0.2 gr, something like that. However, it's not so much that the actual [final] charge weight would be off with the MS attached, it's more than deciding which charge weight is the best can be more difficult.

Thanks.

 

[snakepit]

Nomad47 started a Thread/Topic on 08/30/13 called "Stock Mounted MagnetoSpeed" describing the stock mount he built for his MagnetoSpeed and it includes pictures. I think this was a prototype he built for testing.

Maybe he will respond and give us a update.

 

[snakepit]

On the MagnetoSpeed web site they have some high speed photos showing the the bullet passing over the bayonet sensors ahead of the muzzle blast.

www.magnetospeed.com/pages/tech-info

 

[Raythemanroe]

Nomad47 started a Thread/Topic on 08/30/13 called "Stock Mounted MagnetoSpeed" describing the stock mount he built for his MagnetoSpeed and it includes pictures. I think this was a prototype he built for testing.

Maybe he will respond and give us a update.

Did the MS work well this way? I could see that solving my questions..


Ray

 

[BradY]

I actually do look at the data in that way because I am shooting groups/targets with the MagnetoSpeed attached while I'm measuring velocity. I just don't use the MV group spreads for determining optimal charge weight. In general, I would say if everything is working right, they probably wouldn't be off by more than 0.1-0.2 gr, something like that. However, it's not so much that the actual [final] charge weight would be off with the MS attached, it's more than deciding which charge weight is the best can be more difficult.

Thanks.

So simplifying things can we say that for load development using the OCW method and a magnetospeed, a shooter is better off doing their OCW with no magnetospeed attached. Then doing their seating depth tuning with no magnetospeed attached. Once they are happy with their load they can then run the magnetospeed on the barrel and take measurements like ES and SD and if required, modify the load slightly to get the lowest acceptable spread required for their type of shooting.

 

[snakepit]

Nomad47 started a Thread/Topic on 08/30/13 called "Stock Mounted MagnetoSpeed" describing the stock mount he built for his MagnetoSpeed and it includes pictures. I think this was a prototype he built for testing.

Maybe he will respond and give us a update.

Did the MS work well this way? I could see that solving my questions..


Ray

Give Nomad47 a PM, he has always been very helpful to me.

 

[6BRinNZ]

I actually do look at the data in that way because I am shooting groups/targets with the MagnetoSpeed attached while I'm measuring velocity. I just don't use the MV group spreads for determining optimal charge weight. In general, I would say if everything is working right, they probably wouldn't be off by more than 0.1-0.2 gr, something like that. However, it's not so much that the actual [final] charge weight would be off with the MS attached, it's more than deciding which charge weight is the best can be more difficult.

Thanks.

So simplifying things can we say that for load development using the OCW method and a magnetospeed, a shooter is better off doing their OCW with no magnetospeed attached. Then doing their seating depth tuning with no magnetospeed attached. Once they are happy with their load they can then run the magnetospeed on the barrel and take measurements like ES and SD and if required, modify the load slightly to get the lowest acceptable spread required for their type of shooting.

Yeah. To get the best out of Eriks' approach a chrony during load dev is the way to go. I do this by using my old chrony which while not reliable gives me an idea.

I then use the magneto during club days to gather data under match conditions change of season, change of components etc. This is what I did with the 6br last season.

I am definitely going to do this with the .308 as I simply can't get enough bullets to have the luxury of shooting longer strings at the range testing and having enough left over for comps, be they club days, regionals or nationals.

 

[Nomad47]

Nomad47 started a Thread/Topic on 08/30/13 called "Stock Mounted MagnetoSpeed" describing the stock mount he built for his MagnetoSpeed and it includes pictures. I think this was a prototype he built for testing.

Maybe he will respond and give us a update.

Did the MS work well this way? I could see that solving my questions..


Ray

Yes, it worked well attached to the stock. I removed the spacer on the bayo and had the strap loose around the barrel to help keep things centered. But the bayo was definitely NOT attached to or touching the barrel.

Another option: Do your load development and ALL subsequent shooting with the bayo attached. I did that last year. Shot long range steel comps and 270 groundhogs with the bayo attached.

 

[mac86951]

I guess I'll toss my hat in the ring too.

I've done several 223 load work-ups with 16-24" AR barrels, from Pencil to Heavy (0.936 GB dia, with 0.850 Muzzle diameter). In all cases it shifted POI, so it was used during the early stages of load workup, not looking at accuracy. It was as accurate as my PACT in sd and ES, though velocity was offset by +/-~100fps. I wouldn't trust raw velocity from any chrono under $1000 and without NIST stickers, but SD and ES is what we are really interested in anyway and the Magnetospeed did well there.

It was useful to verify the reloading processes and some values to test accuracy, which were later verified without the device attached. Given that you don't have to go down range to change between targets, or move the device from the firing direction, I'd say it is benefits out weight the detriments. If you are concerned about the # of rounds through the barrel (ie 6.5-284 instead of .223) then I'd opt for the traditional route. Otherwise I think it is a useful tool.

-Mac