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squirrel
12-14-2010, 10:58 PM
I bought the Leupold Magnetic Boresighter and its really cool design however they over looked one thing. Its magnetically mounted on the end of the barrel and the designer assumed the barrel end is plum to the bore axis. This might be the case on a match rifle but the flash hider on the AR-15 is not even close to being plum to the barrel axis. I don't have a clue how to turn the flash hider and barrel on the lathe. Any suggestions?

gzig5
12-15-2010, 01:11 AM
I bought the Leupold Magnetic Boresighter and its really cool design however they over looked one thing. Its magnetically mounted on the end of the barrel and the designer assumed the barrel end is plum to the bore axis. This might be the case on a match rifle but the flash hider on the AR-15 is not even close to being plum to the barrel axis. I don't have a clue how to turn the flash hider and barrel on the lathe. Any suggestions?

Probably not what you want to here, but sell the bore sighter. Take the bolt carrier out, block the upper up on sandbags/pillows and look through the barrel from behind at the target. Center the target up in the center of the bore and then move the scope reticule (or iron sights) to the center of the target. It is an iterative process but goes quickly when you've done a couple. I do it from my kitchen table using a wall mounted sun dial at the neighbors house 90yds away as the target. I've never been more than four inches off with first shot (at the range, not the neighbors house), and from then it is just clicks on the knobs.

You might consider getting a new flash hider if yours isn't square on the end. Something doesn't sound right there and I'm not sure lathe turning the end is the fix. Sounds like the threads aren't axial.

38_Cal
12-15-2010, 01:30 AM
out of square muzzle or muzzle brake is the one major drawback to the use of a magnetic boresighter or boresighter arbor. Make up an arbor that's a slip fit in your bore, probably .2175" or so, with a 3/4" dia. "button" on the end so you can slip it into your AR's bore and grab onto the button with the magnetic section of the boresighter. You might even make the button bigger so that if you've got a high mounted scope on the upper you'll be able to locate the grid on the boresighter. Or, sell the Leupold unit & get the Sweeney that Alley Supply sells. You can even use it successfully with iron sights. I've had mine for 30 years, and would not be without it.

David

squirrel
12-16-2010, 10:11 PM
Thank you for the info, I suspected something was a little wacky with that design.

Its even more disappointing just read the package and ITS MARKED MADE IN CHINA.

Just bought a new Leupold Tactical scope for the AR and have not looked at the box to see if it was also made in China, if so it will be on eBay.

carlquib
12-20-2010, 07:39 PM
I still like the Leupold. I don't use it so much to sight in, but once it is sighted in you can use the bore sighter to take an initial reading. Once you know where it is throw the bore sighter in a pack and you can check your rifle any time. If it is dropped or bumped it is much easier to check with the magnetic bore sighter as apposed to sighting in again.

I suppose that if you have a problem with out of square barrels that you could just turn up a spud with a button on the end and use that.

-brian

10KPete
12-21-2010, 03:22 AM
I love my old Sweeney!. Have had it as long as 38_Cal has had his.

Always on within MOA.

Pete

Gently
12-22-2010, 02:14 AM
I bought the Leupold Magnetic Boresighter and its really cool design however they over looked one thing. Its magnetically mounted on the end of the barrel and the designer assumed the barrel end is plum to the bore axis. This might be the case on a match rifle but the flash hider on the AR-15 is not even close to being plum to the barrel axis. I don't have a clue how to turn the flash hider and barrel on the lathe. Any suggestions?

O.K. if the Boresighter is "magnetically" attached then it is not a "Boresighter"
It is simply a lazer attachment.
Get a "real" boresight, usually the diameter and design of the calibre bullet. Insert into the chamber (with the bolt removed) adjust the scope to "X" with the borescope. BAM...Bobs your uncle, Done!

Remember to sight the weapon in for the proper distance of the round you are firing (most common) usually 100 yards. If you have A chrony with the firing tables you could set at 50 yds and adjust.

And I believe the Flash supressor is pinned or welded on the barrel.The only one with a Screwed on Flash supressor is the LAR type rifle, and I have pinned a few of them...they will fall off!

But again if it does not go IN THE BARREL it may be called a boresight, but all it really is is a lazer, A true boresighter ALWAYS is inserted in the chamber and actually looks like the brass for the round. They aint cheap, I think midway has a set for around 300.00 Last time I checked. My set cost 525.00 but I sight a lot of rifles for folks.

Or you could pull the bolt (bolt action and M16 type) and look down the barrel and adjust the scope.

10KPete
12-22-2010, 03:26 AM
We seem to have some confusion here.........

There is a big difference between a lazer bore-sighter and an optical collimator.

The Sweeney and the magnetic Leupold are optical collimators.

Pete