Re: Signs of a canted scope?
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: KS</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Carter Mayfield</div><div class="ubbcode-body">Here are some calcs for cant for a standard .308 running FGMM. Cant varies by drop, so if you are running faster, cant makes less of a difference, if you are running slower, it makes more difference.
range 1 deg 2 deg
yds inches inches
100 0.07 0.14
200 0.22 0.43
300 0.48 0.96
400 0.89 1.77
500 1.46 2.92
600 2.24 4.47
700 3.26 6.52
800 4.59 9.18
900 6.29 12.57
1000 8.43 16.85
As you can see, cant doesn't start making a real difference until 500 yards or so. You can probably see 2 degrees of cant. 1 degree of cant is hard to discern.
After doing the RO trigger school on this sight, I realize that a lot of my windage error is from poor trigger control. It doesn't show up much at close distances.
If you have a cant problem, an anti-cant will fix it easy enough. It is practically a must at longer distances, for me at least, but I am really bad at discerning cant. </div></div>
OK Carter I'll throw a wrench in the works. I know you are talking centerfire but.........if you were shooting rimfire at longer distances would it still not be a big deal. Being you have cranked in more elevation instead of just distance would that not matter? If a 22 is dead nuts on at 50yds and you add 25moa to the scope wouldn't it still throw it WAY off becasue of the scope adjustments more so than distance to the target?
I hope you know what I'm asking. I'm not even sure if I know what I'm asking????
Seems like Greg's way takes this into consideration.
I'm not saying you are wrong just tryin' to understand.
thanks,
Keith </div></div>
Yes, a rimfire will need an anti-cant device for anything over 50 yards and it would be a good idea at 50 yards. I am not talking about scope zeroes, I am talking about actual drop if the gun were aimed exactly horizontal. What you do to zero a scope is you move the vision path (I don't know the technical term) downward to compensate for bullet drop.
When you cant the scope, rather than this path going straight down to adjust for gravity, it moves down and to the side. As a result, it undercompensates for gravity and over compensates on the horizontal (windage). The numbers above are not precise. All they are is the Sin of the cant angle times the amount of drop if the bullet started with a flat trajectory.
With a 22LR, the effect of cant is as follows:
range 1 deg 2 deg
yds inches inches
50 0.10 0.20
100 0.32 0.65
150 0.73 1.46
200 1.34 2.67
250 2.16 4.33
300 3.24 6.47
I am not really trying to counter Greg's way... Greg's idea is right... I was just pointing out the effect of cant. For centerfire at shorter distances, it is miniscule. At longer distances, it starts to make a difference. For rimfire, it makes a difference at almost all ranges; it just depends on the drop for whatever bullet you are using.
I was just trying to quantify how far off you are. If you are playing at longer ranges, buy an anti-cant device, mount it to your scope, and center it to the scope using a plumb bob. Some people mount to the pic rail, but I think you are taking too many leaps of faith about things being square. If you mount directly to the rail, the reticle needs to be square to the scope, the scope needs to be square to the rail, and the ACD needs to be square to the rail. Little errors in all of these can start to add up.
