oldotter,
Good for you, but my experience is completely different--as is that of many other shooters.
I have seen plenty of rifles where point of impact AND group size have been affected considerably. One example was during a range session with three friends. I got there a little later than the others, and they were puzzling over a new (and very accurate) rifle one of them had just tested with handloads. One load had shot more accurately than several others, so they put a Magnetospeed on the muzzle to chronograph the vleiciuty. The load not only didn't shoot very well with the chronograph on the muzzle, but 2-3 inches higher.
Sometimes POI and group size don't change with a Magnetspeed on the muzzle, but in my experience that can only be counted on with heavy-barreled rifles. With sporter-contour barrels, of any weight, there is a distinct possibility of variations both in accuracy and POI.
Since I regularly shoot 4-5 rifles during each range session, using a Magnetospeed mounted on the barrel means I have to shoot everything twice, to make SURE there isn't a difference in group size--and sighting-in requires more shooting as well. Using the mounted MS saves time, money and barrel life.
Edited to add that mounting the Magnetospeed on a stand also saves time in another way: I don't have to keep switching it from rifle to rifle during a range session, instead just shooting over it, much like a light-screen chronograph.
Last edited by Mule Deer; 07/05/20. Reason: Additional info
