Re: MagnetoSpeed Chronograph Review
I received my MagnetoSpeed a couple weeks ago, and finally had a chance to take it out to the range today for some quick testing.
<span style="font-weight: bold">The Good</span>
Bottom line is that it's great. It's incredible just how much more convenient it is than a traditional chronograph. I don't ever want to have to set up a chrono on a tripod, line it up, hope I don't shoot it, worry about the weather, etc. again. The user interface and features of the readout is great; so much more sane than my other chrono (a Chrony Master Beta). Popped the SD card out of the Magnetospeed and into my computer, and there's a text file (CSV with summary computations mixed in) with all of the data.
I only did limited, not well-controlled testing today, but the numbers seem accurate compared to past data I have on this same round (Federal GMM 175gr .308). With my muzzle brake on my 26" barrel, 5 shots read an average of 2631 fps, SD=9, ES=22. Last time I measured (a different lot number) with my Chrony I got an average of 2638 fps, SD=12. I would have expected the Magnetospeed number to be slightly higher since it's measure closer to the barrel, but we're talking an expected 10fps or so, and since these are different ammo lots it's all well within my expected margin of error.
<span style="font-weight: bold">The Bad</span>
Unfortunately, (as predicted by others in this thread) one of the plastic bits broke as soon as I tried to put it on my barrel. I did a trial run of attaching it before going to the range and it worked fine. When I got to the range, though, I put it around the barrel, cinched the strap around the barrel, then pushed down on the plastic lever to make it tight. That's when I heard the "snap" sound, and one of the thin portions of that plastic lever snapped in half. The other side was still intact, so I loosened the strap and was able to snap down the piece so that it wasn't particularly tight, and it lasted the shooting session without causing problems.
Hard to see in the picture I took when I got home, but here's where it broke:
I'll email the manufacturer and see if they can send me a replacement piece or if they have ideas how to improve the reliability of that in the future... it does seem fundamentally flawed since the whole point of that lever is to tighten the thing down with lever force multiplication... having a small amount of plastic taking that much torque seems like it's asking for trouble.
In any case, I was lucky that it didn't break badly enough, so I was still able to use it. The benefits outweigh tradition chronographs so much that I would still gladly buy the Magnetospeed despite the risk of that piece breaking, and I'll just be a little more sensitive to how much I pre-tighten the strap in the future (I'll also reserve final judgement until I hear back from the company to make sure they do the right thing and at least send me a replacement for the broken piece).
<span style="font-weight: bold">POI Shift</span>
As expected and others have pointed out, having the bayonet hanging from the barrel does cause a POI shift. I will need to test this more carefully when I have more time, but I tried four configurations (in the following order, so the barrel was also heating up over the testing session in this order):
1. Magnetospeed: NO, Muzzle Brake: YES (my "normal" configuration)
2. Magnetospeed: YES, Muzzle Brake: YES
3. Magnetospeed: YES, Muzzle Brake: NO
4. Magnetospeed: NO, Muzzle Brake: NO
I shot five rounds in each configuration. Here's the result:
With the muzzle brake on, the POI shift appears to be about 1" of elevation. Without the muzzle brake on, the POI shift appears to be about or a little less than 1/2". (This is at 100 yards). Again, I didn't allow much barrel cooling times between groups, and we had very variable weather -- changing from raining to clear and sunny over 20 minutes while I was doing these shot strings) so there could be other contributing factors. It does appear that there's a larger impact to POI with the muzzle brake attached, though.
There's no obvious impact to precision (hard to say for certain at 100 yards, though), just a change in POI. If that continues to be the case, I don't mind the POI shift given how much more convenient this is than traditional chronos.
That's it for now. They need to solve the problem of the strap tightening lever just asking to be broken, but otherwise the Magnetospeed is really cool and works well. Three guys at the range came by to take a look...it definitely attracts attention since nobody knows what it is! All of them agreed that someone should have thought of this years ago.
