i recently bought one of the little magnetic boresighters leupold makes. while it will not replace my old sweeny site aliner, it is a very usefull tool. the magnet is sufficently powerful to hold on to the barrel and the height adjustment it gives (3") makes it useful for things i can't use the site align for. such things as AR's with their high mount scoles and muzzle brakes, 50 cal rifles, odd calibers that you don't have spuds for etc. are all doe handily with the leupold tool. while i have never used them as a checking tool, i do use them quite a bit for scope mounting and this little tool fits the bill quite nicely

I use one and am satisfied with it.

I keep one in the range bag for the newbies that are having trouble, & I like the laser bore sighters myself & keep specific cases for .270W/7mm WSM/.223Rem.

I like mine.

LWD

OK,
I am going to ask a stupid question. Since I have only used the spud type, how does the Leupold index with the barrel? I mean a collimator with an arbor will be centered and the height is a fixed figure. But with the Leupold, you could stick the barrel anywhere on the boresighter. How does it "know" the distances so you can make correct adjustments. You can tell I have not studied the Leupold item very closely.

that question is one of the reasons i didn't buy one before. it doesn't make any difference in reasonable height;. think about it - the spud is always the same height, but the scope might be on low rings or high and it still works. the height is adjustable on the leupold so you can clike the little lit grid up and down to roughly match the csope height, even on things like AR's that are to high for the spud. and the little grid has a little led - and thats nice

That is right, but I still don't get it. How does it center or offer any correlation to height or side to side? It looks to me like you could stick it on the end of the barrel off center, then what good would that do you? At least with the arbor all you have to worry about is the elevation. If it is say 1/8 inch to the left or right of center then that would make a big difference even at 100yds.

The only problem I've found with the magnetic Leupold is if your barrel isn't square with the bore and/or the ring bases holding the scope.

It's all about the angles and if they are off a bit your zero will not align with the bore sighter. You can get repeatable zero's once you calibrate your particular rifle (taking a sope off and putting it or another back on), but your alignment on a new rifle may be a bit off. It should get you on paper, but may not be as close to the bull as you would have liked.

I like mine becaue it's small and I can check my zero after I've put the gun on a plane or been on a long road trip.

I've indexed all my rifles and keep records of where their zero's are.

The Sweeny Site-A-Line is my top pick after 30 years of trying them all. The Sweeny has a tool to use on AR's. I plan to ask for a .510 spud.