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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Effects of Rifle Canting on LR Accuracy
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<blockquote data-quote="Brent" data-source="post: 28651" data-attributes="member: 99"><p>This is zeroed at 1000 yards, then 12 degrees of cant were added to see its effects. As you can see, it altered the zero range by 5yds also.</p><p></p><p>CALIBER: 300 Ultra Mag</p><p>MUZZLE VELOCITY: 3100 fps</p><p>BULLET WEIGHT: 200 gr.</p><p>BALLISTIC COEFFICIENT: 0.588</p><p>SIGHT HT.: 1.76 in. (1.8"/12°)</p><p>ZEROED AT: 995 Yds.</p><p>INCLINE ANGLE: 0 deg.</p><p>WIND: 0 mph</p><p>STANDING TARGET</p><p>ATMOSPHERE: Std. 300 ft. </p><p> 59° F./300 ft./29.53 in. HG/78% R.H.</p><p>'G1' STANDARD FLAT BASE</p><p></p><p>Range- Vel.- Energy- Drop- Path---- Defl.- Time- Lead-</p><p>Yards- fps- Ft.Lbs.- Inches- Inches- Inches- Sec.- Inches-</p><p></p><p> 000 3100 4268 0.00 -1.76 -0.37 0.000 0.0</p><p> </p><p>100 2934 3822 1.88 24.00 5.31 0.099 0.0</p><p> </p><p>200 2774 3417 7.79 45.72 10.99 0.205 0.0</p><p> </p><p>300 2620 3047 18.23 62.91 16.68 0.316 0.0</p><p> </p><p>400 2471 2710 33.74 75.04 22.36 0.434 0.0</p><p> </p><p>500 2326 2403 54.95 81.46 28.05 0.559 0.0</p><p> </p><p>600 2187 2124 82.60 81.45 33.73 0.692 0.0</p><p> </p><p>700 2052 1870 117.52 74.17 39.42 0.834 0.0</p><p> </p><p>800 1922 1641 160.70 58.62 45.10 0.985 0.0</p><p> </p><p>900 1798 1436 213.30 33.65 50.79 1.146 0.0</p><p></p><p>1000 1680 1253 276.67 -2.08 56.47 1.319 0.0</p><p></p><p>TRAJECTORY CROSSES LINE OF SIGHT AT 6.4 & 995 yds. </p><p>PATH IS 82.31 IN. OVER LINE OF SIGHT AT 551.8 yds.</p><p></p><p></p><p>Testing to see how this chart posts. <img src="http://images/icons/wink.gif" alt="" class="fr-fic fr-dii fr-draggable " style="" /> </p><p></p><p>Dave, </p><p>you're right. I'm refering to actual rifle canting, scope cant when mounting will also have an effect when dialing out to a farther range, bullet deflection just is not the same amount as canting the rifle for the same degree of cant... or is it? </p><p></p><p>The RSI Shooting Lab program predicts "rifle cant", with a properly aligned scope, at what ever the range, only now you just tell it how much the rifle is canted. The program will calculate the cant in the "deflection" column, adding or detracting from the wind deflection value, if wind is also entered. For this chart, wind is set to zero and cant is the total deflection cause. Canting is entered - for left cant, + for right cant.</p><p></p><p>A 12 degree cant error in the mounting of the scope would be relative to the range it was zeroed at, and error would only begin to increase with distance beyond that if the rifle is level and if elevation setting is adjusted and the only cause for it... effective windage would be changed from the vertical adjustment by an amount relative to the cant angle in the scope. Vertical MOA calibration would, at some point, be noticably affected as the adjustment isn't perfectly vertical anymore, and has some hoizontal movement.</p><p></p><p>Lets assume the scope is mounted perfectly, with the vertical hair intersecting the bore line and just look at the rifle canting effect, I'll have to think a bit more on the scope canting and how you'd figure that closely. Dave, any ideas?</p><p></p><p>I'm fixing to look at a 175gr SMK at 2600 fps, G1 BC of .505 and get back to this thread. I know you're familiar with it well. At 100 yards, canting over the rifle 90 degrees error, horizontal deflection should be equal to the bullet drop plus the scope height in inches, vertical drop would be actual for a 100yd shot... if the gun's perfectly zeroed at 100 yards. </p><p></p><p>Back in a few...</p><p></p><p></p><p>Here's another chart, same as above only with a 100 yard zero, same 12 degrees cant.</p><p></p><p></p><p>CALIBER: 300 Ultra Mag</p><p>MUZZLE VELOCITY: 3100 fps</p><p>BULLET WEIGHT: 200 gr.</p><p>BALLISTIC COEFFICIENT: 0.588</p><p>SIGHT HT.: 1.76 in. (1.8"/12°)</p><p>ZEROED AT: 103.4 Yds.</p><p>INCLINE ANGLE: 0 deg.</p><p>WIND: 0 mph</p><p>STANDING TARGET</p><p>ATMOSPHERE: Std. 300 ft. </p><p> 59° F./300 ft./29.53 in. HG/78% R.H.</p><p>'G1' STANDARD FLAT BASE</p><p></p><p>Range- Vel.- Energy- Drop- Path---- Defl.--- Time- Lead-</p><p>Yards- fps- Ft.Lbs.- Inches- Inches- Inches- Sec.- Inches-</p><p> </p><p>000 3100 4268 0.00 -1.76 -0.37 0.000 0.0</p><p> </p><p>100 2934 3823 1.88 0.01 -0.06 0.099 0.0</p><p> </p><p>200 2774 3417 7.79 -2.27 0.25 0.205 0.0</p><p> </p><p>300 2620 3047 18.23 -9.07 0.56 0.316 0.0</p><p> </p><p>400 2471 2710 33.74 -20.93 0.87 0.434 0.0</p><p> </p><p>500 2326 2403 54.95 -38.50 1.18 0.559 0.0</p><p> </p><p>600 2187 2124 82.59 -62.50 1.49 0.692 0.0</p><p> </p><p>700 2052 1870 117.51 -93.78 1.80 0.834 0.0</p><p> </p><p>800 1922 1641 160.70 -133.32 2.11 0.985 0.0</p><p> </p><p>900 1798 1436 213.30 -182.29 2.42 1.146 0.0</p><p></p><p>1000 1679 1253 276.68 -242.02 2.73 1.319 0.0</p><p></p><p></p><p>VITAL ZONE = 0 IN. POINT BLANK RANGE = 105.7 yds.</p><p>TRAJECTORY CROSSES LINE OF SIGHT AT 90 & 103.4 yds. </p><p>PATH IS 0.01 IN. OVER LINE OF SIGHT AT 96.9 yds.</p><p></p><p>[ 09-25-2003: Message edited by: Brent ]</p><p></p><p>[ 09-25-2003: Message edited by: Brent ]</p><p></p><p>[ 09-25-2003: Message edited by: Brent ]</p></blockquote><p></p>
[QUOTE="Brent, post: 28651, member: 99"] This is zeroed at 1000 yards, then 12 degrees of cant were added to see its effects. As you can see, it altered the zero range by 5yds also. CALIBER: 300 Ultra Mag MUZZLE VELOCITY: 3100 fps BULLET WEIGHT: 200 gr. BALLISTIC COEFFICIENT: 0.588 SIGHT HT.: 1.76 in. (1.8"/12°) ZEROED AT: 995 Yds. INCLINE ANGLE: 0 deg. WIND: 0 mph STANDING TARGET ATMOSPHERE: Std. 300 ft. 59° F./300 ft./29.53 in. HG/78% R.H. 'G1' STANDARD FLAT BASE Range- Vel.- Energy- Drop- Path---- Defl.- Time- Lead- Yards- fps- Ft.Lbs.- Inches- Inches- Inches- Sec.- Inches- 000 3100 4268 0.00 -1.76 -0.37 0.000 0.0 100 2934 3822 1.88 24.00 5.31 0.099 0.0 200 2774 3417 7.79 45.72 10.99 0.205 0.0 300 2620 3047 18.23 62.91 16.68 0.316 0.0 400 2471 2710 33.74 75.04 22.36 0.434 0.0 500 2326 2403 54.95 81.46 28.05 0.559 0.0 600 2187 2124 82.60 81.45 33.73 0.692 0.0 700 2052 1870 117.52 74.17 39.42 0.834 0.0 800 1922 1641 160.70 58.62 45.10 0.985 0.0 900 1798 1436 213.30 33.65 50.79 1.146 0.0 1000 1680 1253 276.67 -2.08 56.47 1.319 0.0 TRAJECTORY CROSSES LINE OF SIGHT AT 6.4 & 995 yds. PATH IS 82.31 IN. OVER LINE OF SIGHT AT 551.8 yds. Testing to see how this chart posts. [img]images/icons/wink.gif[/img] Dave, you're right. I'm refering to actual rifle canting, scope cant when mounting will also have an effect when dialing out to a farther range, bullet deflection just is not the same amount as canting the rifle for the same degree of cant... or is it? The RSI Shooting Lab program predicts "rifle cant", with a properly aligned scope, at what ever the range, only now you just tell it how much the rifle is canted. The program will calculate the cant in the "deflection" column, adding or detracting from the wind deflection value, if wind is also entered. For this chart, wind is set to zero and cant is the total deflection cause. Canting is entered - for left cant, + for right cant. A 12 degree cant error in the mounting of the scope would be relative to the range it was zeroed at, and error would only begin to increase with distance beyond that if the rifle is level and if elevation setting is adjusted and the only cause for it... effective windage would be changed from the vertical adjustment by an amount relative to the cant angle in the scope. Vertical MOA calibration would, at some point, be noticably affected as the adjustment isn't perfectly vertical anymore, and has some hoizontal movement. Lets assume the scope is mounted perfectly, with the vertical hair intersecting the bore line and just look at the rifle canting effect, I'll have to think a bit more on the scope canting and how you'd figure that closely. Dave, any ideas? I'm fixing to look at a 175gr SMK at 2600 fps, G1 BC of .505 and get back to this thread. I know you're familiar with it well. At 100 yards, canting over the rifle 90 degrees error, horizontal deflection should be equal to the bullet drop plus the scope height in inches, vertical drop would be actual for a 100yd shot... if the gun's perfectly zeroed at 100 yards. Back in a few... Here's another chart, same as above only with a 100 yard zero, same 12 degrees cant. CALIBER: 300 Ultra Mag MUZZLE VELOCITY: 3100 fps BULLET WEIGHT: 200 gr. BALLISTIC COEFFICIENT: 0.588 SIGHT HT.: 1.76 in. (1.8"/12°) ZEROED AT: 103.4 Yds. INCLINE ANGLE: 0 deg. WIND: 0 mph STANDING TARGET ATMOSPHERE: Std. 300 ft. 59° F./300 ft./29.53 in. HG/78% R.H. 'G1' STANDARD FLAT BASE Range- Vel.- Energy- Drop- Path---- Defl.--- Time- Lead- Yards- fps- Ft.Lbs.- Inches- Inches- Inches- Sec.- Inches- 000 3100 4268 0.00 -1.76 -0.37 0.000 0.0 100 2934 3823 1.88 0.01 -0.06 0.099 0.0 200 2774 3417 7.79 -2.27 0.25 0.205 0.0 300 2620 3047 18.23 -9.07 0.56 0.316 0.0 400 2471 2710 33.74 -20.93 0.87 0.434 0.0 500 2326 2403 54.95 -38.50 1.18 0.559 0.0 600 2187 2124 82.59 -62.50 1.49 0.692 0.0 700 2052 1870 117.51 -93.78 1.80 0.834 0.0 800 1922 1641 160.70 -133.32 2.11 0.985 0.0 900 1798 1436 213.30 -182.29 2.42 1.146 0.0 1000 1679 1253 276.68 -242.02 2.73 1.319 0.0 VITAL ZONE = 0 IN. POINT BLANK RANGE = 105.7 yds. TRAJECTORY CROSSES LINE OF SIGHT AT 90 & 103.4 yds. PATH IS 0.01 IN. OVER LINE OF SIGHT AT 96.9 yds. [ 09-25-2003: Message edited by: Brent ] [ 09-25-2003: Message edited by: Brent ] [ 09-25-2003: Message edited by: Brent ] [/QUOTE]
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Effects of Rifle Canting on LR Accuracy
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