Magnetospeed and barrel...

Aloha,
I'm using the Magnetospeed Sporter on the TC Compass 6.5 Creedmoor. I notice that the chrono moves back and forth on the barrel and suspect it impacts the accuracy. I think it bumps back off the muzzle brake after each shot. I tighten the strap and the screw as much as I can (without breaking it). I've tried both thin and thick pads, and the thick seems to work better. I used a wire brush on the pads to increase friction. I bought new pads from Magnetospeed but still seems to move. Doesn't seem to be a problem with my other rifles. Any suggestions?

https://ronsreloading.wordpress.com/

 

Mine does the same thing on my Savage barrels. Just thought of maybe removing any rust preventive you use on the exterior of the barrel, and/or try using a small patch of the shelf liner/stuck pickle jar lid gripper material in between the barrel and the MS pad.

 

Haven't had that problem at all with mine.
Are you using the rubber pad on top of the barrel?

 

I had the same sliding problem until I cinched it real tight, then only slightly. Just something you have to watch out for. I wouldn't accuracy test with it seeing as it is attached to the barrel, it would have to change/interfere with the barrel harmonics.

 

Thick rubber "packing" sheet, cut to fit.

https://www.rubbercal.com/sheet-rub...zZGHOO5cYFwG1yP3wRYW63QFhnVIfIcBoCC30QAvD_BwE

Lowes, most auto parts stores have 'em.

 

Oh, and I both used the Magneto Speed attached to the barrel and to the suppressor with no negatve impact on accuracy. YMMV.

Besides... its not a permanent attachment. Its just to get velocities... maybe a total of 10 rounds fired.

 

The Magnetospeed strap is fairly terrible in several ways and the tightening screw doesn't have enough travel. Not much to do about that except make sure it's real tight, then turn the screw.

I also often use the second rubber pad under the strap on top. The strap itself is slippery, so this gives double the grip surface area, works well.

If you have a thin tapered barrel, it can still be a problem, especially on older sporting guns with slick blued finishes and lots of oil. I like the idea of sticking some shrink tube on there, (leave a thread under it or something to remove without risking nicking the metal with a knife when you do remove it). But, I have lots of good size shrink tube around, you may find something else around the shop works better.

When I have had slips, I have seen no apparent change in the measured velocity during slips, compared to later when I remount to the same barrel. Bullets go real fast, so the gun doesn't move hardly at all while the bullet is in the barrel (or passing the magnetospeed) so even if the unit was entirely free to slide (as long as properly aligned) I bet you'd get an accurate measure.

Slightly OT: The overall design of the device is one thing that makes me like the Magnetospeed. If it slips off, it falls down, away from the bullet track. You get no read, but also do not shoot the unit. I have replaced too many Chrony units from mistakes, want to keep this one.

Back OT: I tightened one up oddly once, using extra padding incorrectly, and did manage to tilt the measuring unit, grooved it very lightly. Make SURE you are applying any extra pads and anti-slip bits uniformly, and stick a rod in the muzzle before you load and fire to make sure it'll clear. (Tip: not a steel measuring rod. It's actually got a magnet in it. Ask me how I know).

 

Get the MagnetoSpeed OFF the barrel if you can. That's what all the ELR guys are doing.

https://mkmachining.com/product/mk-machining-gen-iii-magnetospeed-mount/

http://www.davidtubb.com/David-Tubb-Rifle-Gun?product_id=199

 

I used a rosin bag before strapping it on. It is messy but works ok

 

Accuracy is impacted with a MS attached..... do not develop group loads with magneto attached.

 

The thing can be a real nuisance to put on, I could actually use another hand most of the time I always use the rubber pad but I have a friend who never uses it and has no problem.
I have some self fusing tape for use on electrical connections, it can be stretched and wrapped back on its self making a stable/sticky platform for the Magnetospeed, then cut off afterword.
I wonder if that might be useful for problem barrels, it should be able to get the tape at any big box store like Lowes or Homedepot .

 

I only didn't mention fusing tape (and related rubber repair tapes) besides the fact most people don't know what they are, because it is usually overlapped, so I worried about suggesting something that may make the device not parallel to the barrel.

Should grip well and come off, yes. Used it for that on non-electrical things not unlike this. But make sure in this case it is spiral wrapped without any overlap over the area where the sensor base is in contact.

 

Problem fixed.

 

Great stuff everyone. I did see the double pad trick a long time ago and forgot about it. If that doesn't work, I'll try the rubber sheet, rosin bag and/or fusing tape.



The mounts are interesting but at what point should I just buy the Labradar instead.

 

Hey that looks great and will solve the problem of the Magnetospeed affecting where the gun prints.

 

I've experimented with the bayonet at different heights relative to the bore and have changed the POI up to seven inches high. I don't know the aerodynamics behind it, just that it changes the POI even if it's not attached to the barrel.

 

I put a Velcro patch, like you use for mirage shades, on the barrel we’re the strap will be. Keeps them from sliding pretty well.

 

And...

 

An interesting phenomenon. that's what happens when I attach the bayonet to the barrel.
I assumed it was caused by the bayonet altering the barrel harmonics when attached but apparently not I hope someone will come up with an answer.

 

Interesting.

I don't see any change in POI when I attach my Magnetospeed v3 to my Ruger Precision Rimfire. As finicky as a .22LR pill is, I'd think your experience would reflect on mine.



When I attach it directly to my Krieger 26" .308 barrel, I get a vertical POI shift of about 1 mil. And I only get a POI shift as my precision remains good where I get my usual groups in the 3's and once in a while in the 1's . . . with or without the Magnetospeed attached to the barrel. Sooooo???