I received my MagnetoSpeed this week and was able to take it out to the range today for the first time to try it out.
It's extremely easy to use, strap the bayonet sensor to the barrel, tighten it, look down the bore to make sure the bullet has a clear path and plug it into the unit. Took about 90 seconds. I was shooting 6.5x55 from a CG-63 which tapers from 19mm to 17.5mm at the muzzle and I didn't need to use the extra spacer for the bullet to clear the sensor. The strap held tight for the 50 rounds I fired with the bayonet sensor attached, didn't need to retighten once.
It registered each shot, I was shooting my handloads which were Sierra Match Kings and Remington Core-Lokt both 140gr. I didn't have to adjust the unit's settings, the default setting and sensitivity worked just fine. Using the unit is simple, saving each string is simply a matter of pushing the button a couple of times. Once to get to the menu, scroll down to archive and press again; next numbered string appears a couple seconds after that automatically.
As to how accurate it is compared to other units, I can't answer that, this is my first chronograph. Reviews claim it's within less a % of an Oehler, unless proved otherwise I'll take their word for it. I didn't bring my other rounds that I have chronographed on someone else's unit to compare results with, I've never chronographed my 6.5x55 rounds and wanted to do them first.
The reason I bought this is convenience. I live in Northern VA, so the ranges are crowded, usually indoors, and you frequently don't have the luxury of time. I frequent the NRA range a lot, so I needed something that I can set-up quick and is easy to use and this fits the bill perfectly. I also only have to carry a 14x7x2" box, no tripod, and no worrying about lighting. I've only used it once so far, but it did what the makers said it would do and I was very happy with my experience with it today...and will be using it again on the next trip to the range. If I have any problems, I'll update the post
I've been reloading for about 2 years now, so it's about time I got and used a chronograph.
Edit: I almost forgot to mention the effects of the bayonet on accuracy. The rounds I shot were batches I'd shot before, so I knew what they should
do. The only thing I could tell was my POI was about an 1" higher than it would be without the sensor attached. Groupings were about as tight as I normally get. At 50 yards (I was at the NRA range and that's maximum distance) most of my groupings were around 1", some a little tighter at 1/2", about 3 groupings approached 2" and I'm pretty certain it's the shooter fault there...I'm not a competition shooter. But on the CG-63's barrel, it just seemed to move the POI a little higher. The bayonet sensor is very light.