Laser bore sighter - cartridge versus muzzle attached?

[Martin248]

What's the most accurate laser bore sight?

The muzzle mounted ones offer a variety of calibers with a single device, which saves cost, but do they suffer accuracy as a result? Alternately I can imagine that if they don't have tight tolerances, the cartridge installed ones too might wiggle around in there and not necessarily point straight down the bore, though I guess they can't be off by that much for physical reasons.

Any thoughts?

On my norc m14 the muzzle mounted ones seem to require that I take the flash hider off in order to get the attachment into the bore, so on that platform, the cartridge has a definite advantage.

Any differences in brands? Do the tolerances matter that much? There's a big gap in price if you look on ebay ,between some cheap chinese made ones, and pricey brand names. Do you get anything for the extra money?

 

[Ar180shooter]

IMO it doesn't make much of a difference. Boresighters are just used to shorten your sight in process and save ammunition. They will not give you perfect alignment, you still have to go out and properly zero your rifle.

 

[dand883]

I would think that a muzzle mounted one would be less accurate. If it's not absolutly square when you put it on it would point off and you would never know. A cartridge type can be as off as it wants, but if you see it coming out the end of the barrel you know it is lined up enough to make it down the length of the barrel

 

[Miked181]

I use the LaserLyte boresighter, and have found no issues with it wiggling etc... as long as the fit is snug, and you don't have convulsions whilst attempting to sight in the gun, it will give you a reasonable starting point. As stated previously, you will still need to spend some quality time at the range to get it right on.

Mike

 

[Martin248]

A cartridge type can be as off as it wants, but if you see it coming out the end of the barrel you know it is lined up enough to make it down the length of the barrel

Ok... I knew that one day I would regret not paying more attention in trigonometry so forgive me if I make any errors. But here's a rough back of the envelope on the possible inaccuracy of a bore sighter on a .308 caliber rifle with a 20" barrel (like my SPS tactical):

Triangle from the tip of the laser at the center of the bore to the outer rim of the muzzle is 7.62/2mm=3.81mm tall x 508mm long, hypotenuse = 508.014, op/hyp = 0.0075, sin-1(0.0075) = .43 degrees = 25.8 MOA.

So, if they were off, these cartridge laser bore sights could in theory be off by as much as 25 MOA, if the thing were so bad that it were shining from the center of the bore at the breech just missing the lip of the muzzle. Maybe I got my math wrong, but that tells me that the fit of the cartridge is important.

Any thoughts on a good brand, with tight tolerances?

 

[dand883]

Ok... I knew that one day I would regret not paying more attention in trigonometry so forgive me if I make any errors. But here's a rough back of the envelope on the possible inaccuracy of a bore sighter on a .308 caliber rifle with a 20" barrel (like my SPS tactical):

Triangle from the tip of the laser at the center of the bore to the outer rim of the muzzle is 7.62/2mm=3.81mm tall x 508mm long, hypotenuse = 508.014, op/hyp = 0.0075, sin-1(0.0075) = .43 degrees = 25.8 MOA.

So, if they were off, these cartridge laser bore sights could in theory be off by as much as 25 MOA, if the thing were so bad that it were shining from the center of the bore at the breech just missing the lip of the muzzle. Maybe I got my math wrong, but that tells me that the fit of the cartridge is important.

Any thoughts on a good brand, with tight tolerances?

Up to 25 MOA, which is why i would only use one to get me on paper at 25 yards, imagine though if the muzzle mounted one got bent at the point where it comes out of the bore, it could be pointing in any difection at who knows what angle, and is less likely to be noticed if it is off just looking at it.
Either one is likely to get you on paper at 25 though. All of my scopes have been sighted in without bore sighting, and i haven't had any that were so far off that they missed the paper at 25. Maybe i've been lucky, maybe i've used big targets, who knows.

 

[Agent666]

From my experience, if you use the correct arbor, they are reasonably accurate. I suppose a plastic arbor might warp, but I haven't encountered that.

 

[blwebster]

I would not put anything like that into the muzzle end of a decent rifle.

 

[bandit86]

i like my muzzle sighted, I always rotate it 1/4 a few times to make sure it's even closer to true

 

[jt_trouble]

While using a cartridge boresighter, push on the back of the cartridge while it is chambered. A piece of saran wrap on the end of your barrel, and you will see how much the bore sighter moves around.

I use a SL100 from Site Lite and never had a problem with getting all my firearms on paper, and that just it, They are good for getting you on target, but the final zero is up to you.

 

[Joe57]

i like my muzzle sighted, I always rotate it 1/4 a few times to make sure it's even closer to true

Very good young grass hopper!!

 

[Mudduck]

Picked up a a Bushnell magnetic boresighter .... But one of the rifles I was going to use it in has an aluminum brake ... Sight. Should have just got the normal one to start with ... however when I have the time and place I prefer to sight it by looking through the bore - I have found it to be more accurate ..... But then again that doesn't work well with my semi auto .... Can't quite seem to get my eyeball into the chamber. Lol