  | HUGE BC change with opening up the hollow point. |
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10-14-2007, 08:53 AM
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Join Date: Jun 2007
Location: North Idaho
Posts: 1,788
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I discovered the same issue with the 300 gr SMK in the 338 Edge. I trimmed and opened the hollow point, more for expansion purposes than anything. At 1150 yards 1.50 moa lower same speed load etc. Like you shot some more unmodified bullets to the proper point of impact. I did not notice a improvement in vertical group size and could tell little difference in bullet performance so I bagged the extra work for more shooting time.
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10-14-2007, 08:59 AM
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Gold Member
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Join Date: Dec 2006
Location: Dogpatch, NY
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Quote:
Originally Posted by davewilson
i wish i could tell you all about my shooting but when i went to leave this morning, i forgot to put the emergency brake on my truck and went back in the house to get something i forgot. of course the truck went rolling down a fairly big hill, across a normally wet area and bumped into the small stream where it's sitting now. needless to say i didn't go shooting.
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If I did that, I wouldn't tell anybody. No way!!
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10-14-2007, 09:57 AM
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Platinum Member
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Join Date: Feb 2004
Location: Pennsyltucky
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i'm pretty sure it's totaled!
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10-14-2007, 10:01 AM
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Join Date: Apr 2005
Location: Northern UK
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Similar experience with 142 SMK at a 500 yard target the bullets were dropping 10" lower than expected.
I wonder if there would be any merit in the idea of uniforming the meplat so all bullets are exactly equal in dimension and then running the bullets into a point forming die?
What I'm getting at is uniform bullets with a meplat cut to 90 degree of bore,,, but still with a hollow point - (maybe- I know what I mean, but am too dumb to explain)
The bullet would still expand - right?
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10-14-2007, 10:09 AM
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Join Date: Aug 2003
Location: NC, oceanfront
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Interesting problem.
Your BC should not have changed that much. People trim meplats all the time at around 2% loss in BC per .005" cut.
Your describing a 21% loss without cutting, but opening the meplat .005" in diameter?
Is this correct?
Are you sure it isn't opening .05" in diameter?
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10-14-2007, 07:38 PM
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Join Date: Jan 2003
Location: The rifle range, or archery range or behind the computer in Alaska
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MikeCR, you are correct, but remember I also opend the hollow point by 100% from .020" too .040" That is most likely where most of my BC loss is coming from. The widened tip isnt much but the hole in the middle of it is doubled from factory.
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10-14-2007, 08:18 PM
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What lies WITHIN the meplat diameter doesn't affect supersonic BC.
You could pack it full of material, or let it pack with air, the shockwave will bend the same around that point DIAMETER.
So that diameter, the meplat, affects BC greatly. And boring out the hole, without increasing the meplat diameter, should affect nothing at all.
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