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Long Range Scopes and Other Optics
Ring Height
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<blockquote data-quote="Rich Coyle" data-source="post: 1073828" data-attributes="member: 70559"><p>Does the height of the rings above the barrel affect trajectory?</p><p></p><p>Sixty shots says, "Yes<strong>!</strong>" Arbitrarily I decided on a single ten shot group at 100, 200, and 300 yards with two scope heights. According to the computer, if you sight in a firearm at, say, two hundred yards with the low or the high sight, it hits dead on at two hundred yards. Novel concept. The fun information is at one hundred yards or three hundred yards. And beyond.</p><p></p><p>I used a Savage .223 with the 26" blued (not stainless) barrel for the test. A trigger job brought the pull down to about two pounds. Th scope was 8X - 32X Burris target scope.</p><p></p><p>The loads consisted of a 65 grain JLK bullet (.397 sea level ballistic coefficient corrected to .411 for 1100 feet at the Grants Pass range according to the computer), a neck sized, trimmed to length Remington case with a deburred and squared flash hole holding a CCI BR-4 primer. The powder charge was 27 ½ grains of VarGet. The cases had a weight tolerance of .2 grains and have been fired four times. The average velocity for the first thirty was 3,221 feet per second with a standard deviation of twenty-one. </p><p></p><p> The <strong>HIGH</strong> rings: scope 2.2" above the bore. The temperature started at forty-two degrees and went up to forty-eight degrees during the four hour session. All shooting was done at 32X. The targets were five eights inch squares.</p><p> </p><p>The Burris settled on the left two hundred yard target, where it was zeroed, to start. The first five shots appeared to make a group that looked more like a one hundred yard group in the square. I admired the group awhile through the scope. Even considered putting up another target. Being more lazy than vain, I continued shooting until the ten shot group was completed. Three of the next five went inside the original five, but a couple made holes on either side of it. The two hundred yard group had a vertical dispersion of only one half inch. Horizontally it opened up to one and eleven sixteenth inches.</p><p></p><p>Next I went to the one hundred yard target; leaving the zero setting for 200 yards. Shot number seven opened the one hundred yard oval shaped group to five eighths inch. Measuring from the center of the target up to the center of the group showed .63" on the caliper. The program said it would be .86"....not too bad.</p><p></p><p>At three hundred yards, the ten shot group consisted of a round one and eleven sixteenth inches. The three hundred yard group was 5.5 inches low with the 200 yard zero. Barnes said it would be down 5.58 inches.</p><p></p><p> The <strong>LOW</strong> rings: scope 1.68" above the bore.</p><p>The rifle was cleaned and resighted at two hundred yards. The ten shot group of was an enjoyable 1 3/16" group at two hundred yards. Now to the verification groups.</p><p></p><p>At three hundred yards the first eight shots were looking good for a factory rifle: 1½ inches. Number nine and ten were on either side opening it up to 2 5/16". It was 5.94 inches low. The 1.68 inch sight height centered 7/16" lower than the 2.2" sight height. </p><p></p><p> Moving onto the one hundred yard group: It was great<strong>!</strong> All ten shots went into a group of less than a half inch, which could be covered with a penny! The group was one inch above the line of sight. The program said it would be 1.12" high. There is only 1/8" discrepancy between the shooting and the program. There was about 3/8" between the impact points of the high and low rings at one hundred yards. <strong>The high rings hit lower...or was that the low rings hit higher?</strong></p><p> </p><p>In the book GAME LOADS AND PRACTICAL BALLISTICS FOR THE AMERICAN HUNTER, Bob Hagel suggests that we sight our varmint rifles in to hit one inch high at one hundred yards. I did that exercise in the computer. The high rings required an impact point of two hundred nine yards. The low rings needed a sighting of one hundred ninety-three yards. Shots from the HIGH rings would impact .29 inch HIGH at two hundred yards. For the LOW rings, the computer had the bullets hitting .24 inch LOW at two hundred yards. That's more than ½ inch . At three hundred yards, it's more of the same. The high rings are punching holes 5.15 inches low and the low rings are down 6.20 inches. That's more than one inch higher for the same rifle shooting the same bullet at the same velocity under the same conditions.</p><p></p><p>Perhaps the outer limits for the .223 could be extended. Another computer generated range estimate: Three hundred fifty yards. The high rings impact 9.83" low, while the low rings come in at 11.14" down with the 200 yard sighting. For the lower sight to approximately match the higher sight over a three-hundred yard course of fire, one needs almost one hundred feet per second additional velocity....according to BARNES.</p><p></p><p>In conclusion, what can we conclude? <strong>The high rings shoot closer to the line of sight both;</strong> before and beyond the range for which they are sighted. That means flatter trajectory without higher velocity.</p></blockquote><p></p>
[QUOTE="Rich Coyle, post: 1073828, member: 70559"] Does the height of the rings above the barrel affect trajectory? Sixty shots says, “Yes[B]![/B]” Arbitrarily I decided on a single ten shot group at 100, 200, and 300 yards with two scope heights. According to the computer, if you sight in a firearm at, say, two hundred yards with the low or the high sight, it hits dead on at two hundred yards. Novel concept. The fun information is at one hundred yards or three hundred yards. And beyond. I used a Savage .223 with the 26" blued (not stainless) barrel for the test. A trigger job brought the pull down to about two pounds. Th scope was 8X - 32X Burris target scope. The loads consisted of a 65 grain JLK bullet (.397 sea level ballistic coefficient corrected to .411 for 1100 feet at the Grants Pass range according to the computer), a neck sized, trimmed to length Remington case with a deburred and squared flash hole holding a CCI BR-4 primer. The powder charge was 27 ½ grains of VarGet. The cases had a weight tolerance of .2 grains and have been fired four times. The average velocity for the first thirty was 3,221 feet per second with a standard deviation of twenty-one. The [B]HIGH[/B] rings: scope 2.2" above the bore. The temperature started at forty-two degrees and went up to forty-eight degrees during the four hour session. All shooting was done at 32X. The targets were five eights inch squares. The Burris settled on the left two hundred yard target, where it was zeroed, to start. The first five shots appeared to make a group that looked more like a one hundred yard group in the square. I admired the group awhile through the scope. Even considered putting up another target. Being more lazy than vain, I continued shooting until the ten shot group was completed. Three of the next five went inside the original five, but a couple made holes on either side of it. The two hundred yard group had a vertical dispersion of only one half inch. Horizontally it opened up to one and eleven sixteenth inches. Next I went to the one hundred yard target; leaving the zero setting for 200 yards. Shot number seven opened the one hundred yard oval shaped group to five eighths inch. Measuring from the center of the target up to the center of the group showed .63" on the caliper. The program said it would be .86"....not too bad. At three hundred yards, the ten shot group consisted of a round one and eleven sixteenth inches. The three hundred yard group was 5.5 inches low with the 200 yard zero. Barnes said it would be down 5.58 inches. The [B]LOW[/B] rings: scope 1.68" above the bore. The rifle was cleaned and resighted at two hundred yards. The ten shot group of was an enjoyable 1 3/16" group at two hundred yards. Now to the verification groups. At three hundred yards the first eight shots were looking good for a factory rifle: 1½ inches. Number nine and ten were on either side opening it up to 2 5/16". It was 5.94 inches low. The 1.68 inch sight height centered 7/16" lower than the 2.2" sight height. Moving onto the one hundred yard group: It was great[B]![/B] All ten shots went into a group of less than a half inch, which could be covered with a penny! The group was one inch above the line of sight. The program said it would be 1.12" high. There is only 1/8" discrepancy between the shooting and the program. There was about 3/8" between the impact points of the high and low rings at one hundred yards. [B]The high rings hit lower...or was that the low rings hit higher?[/B] In the book GAME LOADS AND PRACTICAL BALLISTICS FOR THE AMERICAN HUNTER, Bob Hagel suggests that we sight our varmint rifles in to hit one inch high at one hundred yards. I did that exercise in the computer. The high rings required an impact point of two hundred nine yards. The low rings needed a sighting of one hundred ninety-three yards. Shots from the HIGH rings would impact .29 inch HIGH at two hundred yards. For the LOW rings, the computer had the bullets hitting .24 inch LOW at two hundred yards. That's more than ½ inch . At three hundred yards, it’s more of the same. The high rings are punching holes 5.15 inches low and the low rings are down 6.20 inches. That's more than one inch higher for the same rifle shooting the same bullet at the same velocity under the same conditions. Perhaps the outer limits for the .223 could be extended. Another computer generated range estimate: Three hundred fifty yards. The high rings impact 9.83" low, while the low rings come in at 11.14" down with the 200 yard sighting. For the lower sight to approximately match the higher sight over a three-hundred yard course of fire, one needs almost one hundred feet per second additional velocity....according to BARNES. In conclusion, what can we conclude? [B]The high rings shoot closer to the line of sight both;[/B] before and beyond the range for which they are sighted. That means flatter trajectory without higher velocity. [/QUOTE]
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