Blew Up My MagnetoSpeed

FearNoWind

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it's a good idea to avoid putting the MagnetoSpeed bayonet harness over the muzzle brake. But if you happen to be napping and make that mistake, you can recover from it without too much difficulty. Carelessness can be costly. Mounting the MagnetoSpeed Chronograph on the muzzle while forgetting that "this rifle has a muzzle brake" isn't the smartest thing I've done and the resulting damage to the bayonet certainly didn't qualify for warranty repair. With nothing to lose (hey, it was already broken) I figured I'd do the surgery and see if I could revive the patient. It became immediately obvious that MagnetoSpeed didn't intend for the bayonet to be disassembled. Careful handling of the box cutter on both sides did a pretty good job of freeing the inner layer of the bayonet up enough for me to remove it. The rear portion of the inner layer (connector jack) was fractured so that end loosened easily. Once I coxed the inner layer out I found two problems. One connection at the jack was broken and, because I pulled a little too hard when removing the inner layer, another connection at the front of the bayonet had also broken lose. Re-soldering the connection at the jack was simple enough. The broken connection at the other end required some planning. I used my band saw to carefully cut a chunk out of both sides at the front, just deep enough to expose the broken connection point. That made it possible to re-solder it too. The fine folks at MagnetoSpeed confirmed my assessment that the bayonet was made of a type of ABS plastic but I couldn't find any ABS in sheet form. I picked up an ABS coupler (99 cents) at the local Home Depot, cut out a section and heated it with a heat gun until it took on an even sheen. Pressing it between a length of steel and a wooden pressure plate solved that problem. A few measurements and a another visit to the band saw gave me the pieces needed to restore the sides of the bayonet using an ABS epoxy.
 

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davkrat

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Sep 18, 2006
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The Motherlode
Ouch. Doing the tubbs final finish this week I was shooting over my chronograph. Somewhere during the 50 round process my seat must have shifted a bit because all of a sudden I heard a TWANG!!!!! The rest of the day I shot without the sky screens. :)
 

mountainman56

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Mar 27, 2014
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Nice repair job! I have been the author of my own demise more often than I care to admit. Some days things go well.........and some days things go "well sh!t" :)
 

Dosh

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Fear, I've never seen the MagnetoSpeed before, only it's praises on this forum. My question is does a braked barrel do this to them or was your occurance unique? Should I stick to my conventional crono? Thanks
 

FearNoWind

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Jul 10, 2012
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North Central Valley California
Fear, I've never seen the MagnetoSpeed before, only it's praises on this forum. My question is does a braked barrel do this to them or was your occurance unique? Should I stick to my conventional crono? Thanks
By all means, if you're considering the MagnetoSpeed I'd recommend it without hesitation. The MagnetoSpeed works very well with a muzzle brake. My reason for selecting it in the first place was the fact that it provided me with reliable data that I couldn't get from the traditional sky screen style of chrono.
What happened in my case was that I got in a hurry and attached the bayonet mount "on" the muzzle brake. Even though the majority of the ports on the muzzle brake were unobstructed, the ports that were covered by the mount provided enough energy to blow the mounting bracket off off the muzzle.
I had used it on this rifle before and I know that it's supposed to be situated behind the brake but in this instance I simply got careless. If I had been paying attention to what I was doing I would never have had the problem.
 

Bbear

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Mar 13, 2007
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318
I too, have 'dinged' my bayonet on my Magnetospeed. Unfortunately, it broke more than I could easily repair. Mine was just a 'tad' bit too high when I mounted it and I nicked it with my 7mm-08.
I have had a couple of other chrony's in my time and this one has been my favorite. Definitely a fan and advise anyone playing with new loads or checking out the fps on their loads to get one. Does it move the POI? Of the 8 rifles that have shot through mine, only one - a pencil-barreled Rem 700 Mtn rifle in 30-06 has had much of any change in POI or in grouping. But, as in all things, YMMV.
 

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