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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
300 SMK's BC???
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<blockquote data-quote="jwp475" data-source="post: 222152" data-attributes="member: 3776"><p>I have found that the Sierra listed BC of .768 to work out very well in my 338 Lapua.</p><p></p><p> The first time that I Chronographed the 300 SMK i got 2820 FPS and I found my drops to be low at distance. I played with the BC all the way to .830 and that didn't make a large enough difference tyo match my drops. Next I decided to recheck my zero and at the last minute I decided to set up the Ohler 35 and re-chrono at the same time. This time I got an average velocity of 2791 and this matches my acctual drops perfectly with the Sierra BC of .768.</p><p> A 29 FPS error in velocity made the difference. The first day that I chrono'ed was a bright sunny day and the chrono was in the sun. The light diffusers were not enough to prevent the false readings. The next time was overcast and I have learned that direct bright sun light can cause a slighltly higher reading.</p></blockquote><p></p>
[QUOTE="jwp475, post: 222152, member: 3776"] I have found that the Sierra listed BC of .768 to work out very well in my 338 Lapua. The first time that I Chronographed the 300 SMK i got 2820 FPS and I found my drops to be low at distance. I played with the BC all the way to .830 and that didn't make a large enough difference tyo match my drops. Next I decided to recheck my zero and at the last minute I decided to set up the Ohler 35 and re-chrono at the same time. This time I got an average velocity of 2791 and this matches my acctual drops perfectly with the Sierra BC of .768. A 29 FPS error in velocity made the difference. The first day that I chrono'ed was a bright sunny day and the chrono was in the sun. The light diffusers were not enough to prevent the false readings. The next time was overcast and I have learned that direct bright sun light can cause a slighltly higher reading. [/QUOTE]
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300 SMK's BC???
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