Bubble levels / anti-cant… Thoughts?

Forums Optics, Scopes, Rings, & Mounts Bubble levels / anti-cant… Thoughts?

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    JWilson
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    Peskadot671

    JWilson

    I use this on all my air rifles.

    They are nice and low profile. I can see the bubble and center on bottom of reticle without any repositioning of my sight picture. I think it aids in building good form and habit for accurate shooting.

    Joe

    Who makes that and where did you get it?

    Knights Armament. Amazon. Not cheap, but nice and low profile. Neither of my R5 platform rifles required shimming. I did shim my R3 application. Works very well for my air rifle applications.

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    Peskadot671
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    Thanks J

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    damienblack
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    Where can I get one of those bubble cant?

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    nervoustrig
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    They can be purchased for under $10 on Amazon and eBay, example:

    https://www.amazon.com/Bubble-Riflescope-Anti-Cant-Shooting-Hunting/dp/B0772LZF9Z

    Why spend more?  Well I’ve heard one complaint from a guy who said the spirits (liquid) in his was viscous and the level would not respond quickly.  I don’t know how common that is.  The ones I’ve gotten under 3 or 4 different names all respond like the level in my Starrett woodworking square, for example. 

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    Doug-T
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    I bought one of the levels in the Amazon link above.  The tube fell out of the housing under normal use and I never found it.

    I have two of these, one on my 3-gun AR and one on my .22 Mrod and they seem much more robust.  https://www.ebay.com/itm/Hunting-Alloy-Bubble-Spirit-Level-for-Optics-Rifle-Scope-Laser-with-30mm-Tubes/292067078646?epid=839402570&hash=item44008df1f6:g:HtUAAOSw4CFY1tKO:sc:USPSFirstClass!97801!US!-1:rk:1:pf:0

     

    My opinion is the further the target the more a level will help you. 

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    nervoustrig
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    Doug, thanks for the warning. That got me wondering…I just compared the Amazon photo some I got on eBay a few months ago and they look identical.  They were dirt cheap, something like $2 ea.  I tried pulling and twisting the level tubes and none of them would budge…but yeah I wouldn’t be surprised if QC is spotty.  

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    teratoma
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    I've noticed a bit of accuracy improvement after adding a bubble on my scope.  

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    Scrufhunter
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    Yeah I can say the level helps a lot especially at longer distance for sure. The 2nd post is the way to set one up. Level the riffle with a bubble level, then the scope to the rifle and then add the anti can't. If you are right handed, put it off the left side, you can close your scope eye and open your non scope to check level. I taught myself to open both eyes to check for can't. It's weird at first, but you'll get used to it. All three levels should read the same.  There are scopes out there that have that anticant built right into the scope so you see it with your scope eye.

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    Scotchmo
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    Scrufhunter

    … Level the riffle with a bubble level, then the scope to the rifle and then add the anti can't. …

    That can work, but your 1st step is not needed. When you align the scope to the rifle, you only need to insure that the reticle intersects the bore. No need for a bubble level when doing that part.

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    Scrufhunter
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    What?  Go read the 2nd post.  You need a level on the gun and scope to make sure they are level on the same plain, that is what aligns the vertical crosshair to the vertical center of the bore and levels the windage to the same horizontal plain as the bore.  I have seen some people use a string to alling the elevation vertical, but The riffle still needs to be level or it will be canted to the scope. Using two bubble levels is the best way to insure retical to bore alignment. 

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    nervoustrig
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    That will only center the reticle to the bore of everything is machined perfectly and the scope rings are perfectly centered over the bore.

    The mirror alignment method sidesteps all of those potential sources of error. 

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    sonny
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    A rifle barrel is round, as long as your cross hairs are plum and level to your target the angle of the rifle doesn't mater as long as your scope is zeroed in that manor. Some top pro shooters cant the scope rather than their heads when shooting off hand standing and win many long distance shooting matches.

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    Scotchmo
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    Scrufhunter

    What?  Go read the 2nd post.  You need a level on the gun and scope to make sure they are level on the same plain, that is what aligns the vertical crosshair to the vertical center of the bore and levels the windage to the same horizontal plain as the bore.  I have seen some people use a string to alling the elevation vertical, but The riffle still needs to be level or it will be canted to the scope. Using two bubble levels is the best way to insure retical to bore alignment. 

    "what aligns the vertical crosshair to the vertical center of the bore"

    The alignment of the vertical crosshair to the bore does not depend on gravity. You can do that if you want, and as long as everything is machined perfectly square, your barrel is perfectly straight, and you use scopes rings that stay centered (BKL for instance), you can get away with using your method. But that is a roundabout way of aligning the vertical crosshair to the bore.

    "Using two bubble levels is the best way to insure retical to bore alignment."

    No – Your method only insures that your vertical reticle is perpendicular to gravity. You never reference the bore. So it is not the "best way". If you want to get sophisticated, you can use an accurate bore collimator which is physically inserted into the bore. I use a mirror which gives me a visual reference to the bore.

     

     

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    Scotchmo
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    sonny

    A rifle barrel is round, as long as your cross hairs are plum and level to your target the angle of the rifle doesn't mater as long as your scope is zeroed in that manor. Some top pro shooters cant the scope rather than their heads when shooting off hand standing and win many long distance shooting matches.

    It matters if you need to shoot at a different distance and don't have the luxury of taking shots to adjust/confirm for a new zero.

     

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    sonny
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    Whats the difference where you put a scope on a round barrel unless your talking about indexing a barrel.

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    ptthere
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    sonny

    Whats the difference where you put a scope on a round barrel unless your talking about indexing a barrel.

     

    After purchasing a scope-mounted anti-cant level and properly mounting it, I can vouch that there can be big differences to be dealt with.

    The first thing that I did was align my scope crosshairs up with a known level object to gravity, similar to a plum line, and then went ahead and mounted the level onto the scope to proper level with it.

    I then cobbled together some level objects around my air rifle to get the stock and barrel as level as I possibly could confirm, which is when I noticed that I did indeed NOT mount my scope properly, it was canted about 3 or 4 degrees clockwise. I then picked my rifle up and shouldered it, and realized that [apparently] I have been in the habit of slightly canting my rifle as I hold it without realizing it.

    In many situations I don't think that a slight cant would "break the bank," but it is an interesting learning experience, considering that I never really investigated the idea of this in my 3+ decades of shooting, even as a sniper. But it makes sense, when you take into account that most scopes are mounted almost 2" or more above the bore, and that the flight path of a pellet has considerable angle and arc in relation to line-of-sight with the view from the scope.

    For instance, I have this particular air rifle sighted in to zero at 27 yards. But the center of the scope is about 2" above the center of the bore. So over the course of 27 yards (about 25 meters) of flight path, the pellet leaves the barrel at an upward angle, technically more upward than what the target is at 27 yards, but gravity starts arcing the trajectory downward at the moment it leaves the muzzle. So the pellet "falls" into the intended vertical POI in the crosshairs at that 27-yard distance. If the scope is canted left or right in relation to the bore, elevation adjustments on the turret (and a converse relation to windage as well) can become inaccurate because every click up/down on elevation will produce a slight deviation in windage as well, even if the windage turret is not touched. I wouldn't be so picky if it wasn't for the fact that the cheap air rifle that I bought is extremely accurate to begin with, so in regards to my luck with it, I am trying to squeeze the most accuracy out of it as possible.

    An extreme.example would be if you sighted in an air rifle like this at 27 yards, but the entire rifle/scope was canted 90 degrees on it's side to the right, with the barrel being on the left, and the scope laying to the right. If you managed to zero it at 27 yards in this condition, you would find extreme deviation beyond that distance. At 50 yards, a simple "holdover" would not be effective, because the pellet would have drifted several inches to the right after it intersected the original sight-path/zero at 27 yards from left-to-right.

    PT

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