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Offline Davemuzz

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Rising Bullets????
« on: November 16, 2005, 03:23:49 PM »
I bot a new (new to me) 223 14" barrel for my Contender and mounted a Leupold 2.5-8 EER scope to the barrel. For my first outing, I loaded some FMJ 55 grain's over WIN 748.

Now, I shot about 10 rounds or so at 25 yards to get the scope closer to zero as it was shooting about 12" high to begin with. So I then moved to the 50 yard target and got it to hit the center with a few more adjustments. So, I'm smiling like a chesser cat cause this thing is shootin really good.

Now I move to the 100 yard target. I shoot 3 rounds and each round is 5.5" high of center. Nice tight groups, but five plus inches higher? I didn't have time to center it at 100 yards, darkness was setting in.

Any thoughts?

Dave.
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Offline KN

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Rising Bullets????
« Reply #1 on: November 16, 2005, 04:08:53 PM »
Simple, Your bullet has not hit the top of its arch yet at 50 yds. Its still climbing. I don't have my ballistics software handy to tell you more closely what you should be seeing. As the bullet exits its travelling upward in an arc. Thats why you need to check zero at different distances so you will know if you need any hold over for longer shots.  KN
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Offline KN

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Rising Bullets????
« Reply #2 on: November 16, 2005, 04:20:39 PM »
Did some rough calculations. If you zero at 25, (I used a Sierra 55gr spitzer) you should be about 3" high at 100. Thats figuring 3000fps. The farther out you zero the less it shows up at closer ranges because of the arc. Find some ballistics software and play around with it. You will be amazed at how different things are than you thought they should be.  KN
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Offline Redhawk1

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Rising Bullets????
« Reply #3 on: November 16, 2005, 04:33:46 PM »
That is why I get my gun on paper at 25 yards and then shoot at 100 yards and do my final sight in.  Then I go back and see where I am at at 25 and 50 yards.   :D
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Offline **oneshot**

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Rising Bullets????
« Reply #4 on: November 23, 2005, 03:20:32 PM »
Depends on your scope mounts and how high they sit your "line of sight" over the barrel.  If your line of sight is 1" over the barrel versus 1 1/2" will vary your zero comparison from 25 - 100yds.
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Offline jw4570

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Rising Bullets????
« Reply #5 on: November 24, 2005, 02:15:09 PM »
I agree the scope mount above the bore will fool you.  Since many contender mounts sit 1.5-2.0" above the centerline this will case this problem.  It is worse in pistols than rifles due to the short barrel also.

I sight all my guns in with my Laserlyte bore sighter 2" low in my house (I have about a 35' space at one point) and then all hit the paper fine at 25 yards.  I found sighting in for zero caused some serious problems.

JW
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