Magnetospeed Chroy POI Shift

[rosenbaumtravis]

[jimmykan]

Yes, I experienced the same thing. The Magnetospeed changed the POI and group size.

Something to do with barrel harmonics.

I have since bought a LabRadar.

[Fjold]

Yes, it's very common. Actually it's expected to see a difference in the point of impact and the accuracy. During load development develop the accuracy without the magnetospeed mounted and then use the magnetospeed to check the velocity. It takes a few more rounds with every test load to get the average velocity and standard deviation.

[homers]

Biggest drawback to using a magnetospeed

[rosenbaumtravis]

Yes, I experienced the same thing. The Magnetospeed changed the POI and group size.

Something to do with barrel harmonics.

I have since bought a LabRadar.

LabRadar was my second choice because I heard people having bullet read errors. How has it treated you?


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[Citadelgrad87]

Mine shoots noticeably low but group size is unchanged.

http://www.calguns.net/calgunforum/showthread.php?t=1446661

[rosenbaumtravis]

Mine shoots noticeably low but group size is unchanged.

http://www.calguns.net/calgunforum/s....php?t=1446661

Interesting..mine shoots .8 mil high.


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[Sig Marine]

There are mounts available that mount to your chassis or stock that have an extension rod to support the bayonet so it is not mounted to your barrel. Many are using it with success. Some need to be mounted on a chassis with straight sides vs a stock that has a tapered forend; you could probably figure out a way to use shims on a stock if necessary or use the picatinny rail if long enough (as in the picture below). I started using the MK Machine Gen 3 on a chassis and have never dropped a shot in over 600 rounds.

Google Wiser Precision or MK Machining

MK Machine Version

[devster55]

Yes, it's very common. Actually it's expected to see a difference in the point of impact and the accuracy. During load development develop the accuracy without the magnetospeed mounted and then use the magnetospeed to check the velocity. It takes a few more rounds with every test load to get the average velocity and standard deviation.

This is how I work up my loads. Works Perfect.

[jimmykan]

LabRadar was my second choice because I heard people having bullet read errors. How has it treated you?


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Yes, there is a learning curve:

At first I didn't even know how to get it to start taking measurements. I thought it was defective. Then I found out you have to "arm" it and wait for the indicator light to change color before shooting.

Then it was reading velocities that were way too low to be believable. Then I found out you have to set the expected velocity range: Archery (<600 fps), Handgun (600 - 1600 fps), Rifle (1600 fps - 3900 fps)

Now that I have it figured out, it is pretty reliable. Picks up 22LR just fine. It does use the gunshot to trigger the sensors, so not sure how well it would work with suppressed guns.

[rosenbaumtravis]

Magnetospeed Chroy POI Shift

There are mounts available that mount to your chassis or stock that have an extension rod to support the bayonet so it is not mounted to your barrel. Many are using it with success. Some need to be mounted on a chassis with straight sides vs a stock that has a tapered forend; you could probably figure out a way to use shims on a stock if necessary or use the picatinny rail if long enough (as in the picture below). I started using the MK Machine Gen 3 on a chassis and have never dropped a shot in over 600 rounds.

Google Wiser Precision or MK Machining

MK Machine Version

[JackEllis]

If you add something to the barrel, have the barrel touching a rest, or change the way the barrel contacts the stock you're going to have a change in POI.

VarmintAI has some pretty interesting writeups on this topic.

[Sig Marine]

The rifle shoots 0.5 MOA with it off and with it on so I never concerned myself about POI shift; I zeroed the rifle with it on and always shoot in this configuration. If I were going to shoot with and without it, I'd zero in the configuration I was going to do most of my shooting and then use offsets, if necessary, for the other configuration. If you have any questions about doing this, shoot me a PM.

[jwfire25]

If your firing loads to get chronograph data then focus on that and not POI changes or groups opening up. Shoot for groups without it and you'll be good to go. I know guys who's shoot their loads into a pile of dirt 15 yards away because their objective at that point is just to get data. Good luck.

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[Red Mist Maker]

If your firing loads to get chronograph data then focus on that and not POI changes or groups opening up. Shoot for groups without it and you'll be good to go. I know guys who's shoot their loads into a pile of dirt 15 yards away because their objective at that point is just to get data. Good luck.

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THIS^^^
I use mine for the data and just reference the groups. I use a 45 round method of load work up. The test is broken down into 3 separate parts. The last 5 rounds are shot without the magnaspeed for actual group impact