I use a MS Sporter regularly on .22LR to .338 WM. As has been mention by Scott, each rifle is different. I only use it during load development, and honestly, I’ve had a couple of times where I removed the MS and my groups opened up. That one leaves me scratching my head and cussing, but oh well.
....
As you probably know, group size is affected by barrel harmonics. In those couple of odd cases the MagnetoSpeed favorably changed the barrel harmonics for those particular loads, which obviously isn't what you want.
