Magnetospeed POI Change

[minnesotamulisha]

I was at the range on Friday doing some load development. I had loaded up 9 rounds of 3 different charge weights. I shot two, three round groups of each charge weight, without using the Magnetospeed at 100 yards. I then shot one, three round group of each charge weight with the Magnetospeed attached. On each of the charge weights, my POI was dead on at 100. With the Magnetospeed attached, each group had a POI that was about 1.75" higher than my point of aim.

I read that some guys see no change when running the Magnetospeed and some do. I just wanted to post my own experiences.

YMMV.

 

[Comrade Terry]

I was at the range on Friday doing some load development. I had loaded up 9 rounds of 3 different charge weights. I shot two, three round groups of each charge weight, without using the Magnetospeed at 100 yards. I then shot one, three round group of each charge weight with the Magnetospeed attached. On each of the charge weights, my POI was dead on at 100. With the Magnetospeed attached, each group had a POI that was about 1.75" higher than my point of aim.

I read that some guys see no change when running the Magnetospeed and some do. I just wanted to post my own experiences.

YMMV.

My experience is similar to yours.

That's why I only use the Magnetospeed to measure muzzle velocity.

 

[M99]

I've been using the Magnetospeed for the last year and a half. I usually test my groups at 200 and have used it with my 6.5 Creedmore F-Open gun, 308 F-TR gun and 7Rsuam F-Open gun. I found nearly no difference in group size, and less than 1/2 MOA POI change with any of the loads I have tested. I stopped using my Ohler Model 33 because the Magnetospeed was so much easier to use and matched the readings of the Ohler. I guess it just matters what type and caliber of gun you are testing.

 

[asauer]

I would think barrel contour would have a lot to do with it. I don't notice any POI shift on my 25-45 which has a fairly stout barrel, but do on my 220 swift light sporter.

 

[chkunz]

I just bought a Magnetospeed and will start working with it soon. I am going to start by shooting some groups with a rifle and load that I have a good baseline with. For my load development a POI change is not important but an increase in group size would not be helpful. It would be nice to be able to shoot groups and get velocity at the same time. I have data for several ten shot groups with the pet load so I will be able to determine if there is an effect on group size with a high statistical probability.

 

[6BRinNZ]

A friend/customer had a load developed without the Magnetospeed for a 300-WM, and another load developed with the Magnetospeed on for a 6mm-AI. We tested both guns/loads with the Magnetospeed both on and off at 300yds.
The 300-WM groups averaged .3 smaller with it off (8 groups of 3-shots, 4+4 to each).
The 6mm-AI groups averaged .2" larger with it off (8 groups of 5-shots, 4+4 to each).
Both had POI changes from on to off.
Donovan

One question (out of curiosity) - would you have ended up at the same load point? i.e. I appreciate and understand that the agg changed but within that agg was it still the optimal load..i.e. the question ends up being (if load dev done with magneto on) could I find a load (different load) that is smaller if I load dev without the magneto vs does this load shoot smaller without the magneto.

I do my load dev without a magneto but use it during club days on F-class matches. I have used it on a 6br and a .308 all the way out to 1000 yards and with respect to scores and avg x count I can't tell a difference on or off, only POI, so my curiosity is raised as it appears to me that yes there is and would be some impact but the important question is consistency of impact.

TIA

 

[chkunz]

A friend/customer had a load developed without the Magnetospeed for a 300-WM, and another load developed with the Magnetospeed on for a 6mm-AI. We tested both guns/loads with the Magnetospeed both on and off at 300yds.
The 300-WM groups averaged .3 smaller with it off (8 groups of 3-shots, 4+4 to each).
The 6mm-AI groups averaged .2" larger with it off (8 groups of 5-shots, 4+4 to each).
Both had POI changes from on to off.
Donovan

Do you think this is enough data to draw a conclusion from? You did not say if you think the differences you measured were significant or not.

 

[dmoran]

6BRinNZ & T-REX -

More so from the 6mmAI, both were fairly conclusive to my own accuracy expectations. Neither way with neither rifle were like bad accuracy variance, but both had amounts of variance to accuracy and POI shift.
Conducted that test about 4-years ago, when I was deciding to buy one for myself. To me it was conclusive enough that I did not want one for my own use or for the accuracy levels I try to achieve.

My 2-Cents
Donovan

 

[savagedasher]

6BRinNZ & T-REX -

More so from the 6mmAI, both were fairly conclusive to my own accuracy expectations. Neither way with neither rifle were like bad accuracy variance, but both had amounts of variance to accuracy and POI shift.
Conducted that test about 4-years ago, when I was deciding to buy one for myself. To me it was conclusive enough that I did not want one for my own use or for the accuracy levels I try to achieve.

My 2-Cents
Donovan

For the reason listed above. I knew it wasn't something that I wanted.
Larry

 

[M99]

I just bought a Magnetospeed and will start working with it soon. I am going to start by shooting some groups with a rifle and load that I have a good baseline with. For my load development a POI change is not important but an increase in group size would not be helpful. It would be nice to be able to shoot groups and get velocity at the same time. I have data for several ten shot groups with the pet load so I will be able to determine if there is an effect on group size with a high statistical probability.

That's a good point. All of the rifles I have tested it with are very heavy barrel F Class guns. It might be far different with a whippy Hunting barrel.

 

[chkunz]

I just bought a Magnetospeed and will start working with it soon. I am going to start by shooting some groups with a rifle and load that I have a good baseline with. For my load development a POI change is not important but an increase in group size would not be helpful. It would be nice to be able to shoot groups and get velocity at the same time. I have data for several ten shot groups with the pet load so I will be able to determine if there is an effect on group size with a high statistical probability.

That's a good point. All of the rifles I have tested it with are very heavy barrel F Class guns. It might be far different with a whippy Hunting barrel.

My data base is with match rifles with heavy match barrels so as you say they are less likely to be effected but I have the data to compare to so I will know within some reasonable statistical probability. Also I bought the Magnetospeed for convenience over the optical chronographs and if I can not get the two-for-one group and velocity that is no big deal, it will just be a bonus if I can.

 

[minnesotamulisha]

FWIW, My barrel is finished at 22 inches and measures .875 at the muzzle. I would say it's fairly stout.