Re: Near Mfg Alphamount
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: palmik</div><div class="ubbcode-body">is not going to destroy the accuracy of the rifle.</div></div> It doesn't destroy the accuracy, it messes with your ability to hit the target on the first shot! You don't always have exact dope for a shot, and need to rely on drop tables. You also have other variables to worry about like wind changes, you don't want to worry about my scope not tracking vertically because you canted the scope.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: palmik</div><div class="ubbcode-body">as long as you know where that bullet will drop at a distance</div></div>Having a canted rifle doesn't just mess with the 'drop', it messes with the lateral 'drift'.
The error it induces is easy to calculate:
Y = Degree of Cant
X = High Point of the Trajectory
Cosine [(90-Y)*X]
The further you get out, the further off you are.
If you want to read about it, it's well documented here:
http://www.microlevel.biz/cant_errors.html
Run the numbers for .308 shots at 1000 yards, you can decide if the error it induces is negligible.
If you don't shoot longer ranges (800+), then many would say it's negligible. If you have the ability to easily level the rifle & reticle, do it, there's no need to introduce other variables that mess with the results.
From the link I posted:
<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body"><span style="color: #FF0000">I went out to my local shooting range and zeroed the rifle at 400 yards when ScopLevel #1 read level. I shot several groups to be sure of the zero. Next, I rotated the rifle until ScopLevel #2 read level. This produced a cant of 5°. I shot several groups at 400 yards with the canted rifle, and measured the effects each time.
The results? Surprising, to say the least. When canted, the bullets struck about 4 inches to one side. I expected some horizontal movement. But I did not expect the vertical movement to be as large as it was — the vertical impact averaged 3.75 inches low!
The .260 Remington is a cute little cartridge, but it is certainly no barnburner. I took out one of my 7mm Remington Magnums. This is one of the guns I shoot religiously every week at long range. I usually go to the range, place a target, and then try to guess how the environmental conditions will affect my bullet (I use a laser rangefinder, so the range is not a problem). On that particular day when I shot without any canting, my bullets hit 2 inches to the left and 3.5 inches high at 700 yards. I was more than pleased. I then shot with the rifle canted 5°. The results were astounding.
The bullets hit 6 inches to the right of the uncanted shots, but 8 inches low. The next week I broke out my .220 Swift, which at 700 yards has a trajectory similar to the 7mm. Its bullets hit 7 inches low when canted 5°. Both groups were under ½ moa. Future shooting confirmed my initial results.</span></div></div>
So, we have actual data that shows (in the neighborhood of) 1 MOA error, with your theoretical 5 degree cant. Perhaps 5 degrees is too much, and 2.5 is more likely, that's still enough error that it'll cost you points in a match.
I won't be relying on how 'true' or 'square' I think my mount is. I'd rather take in to account all (or at least most) of the pieces of the puzzle. Leveling the reticle should be considered the low hanging fruit in setting up a rifle.
