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Muzzle Velocity and dope do not match
#6868960
08/26/17 12:51 AM
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Joined: Feb 2013
Posts: 1,051
Cattleman
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I shot through a buddies Magneto Speed tonight to finally get some idea of my muzzle Velocity and it's got me scratching my head. I fired three rounds and it gave me a MV of 2670 and a ES of 4 and a SD of 2 out of my 6.5x47 shooting Hornady 143 ELD X over 36 grains of varget. My dope tells me I'm running around 2725ish. What's up?
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Re: Muzzle Velocity and dope do not match
[Re: Cattleman]
#6868977
08/26/17 12:59 AM
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Joined: Apr 2011
Posts: 991
Kevin1
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I would trust the Magnetospeed over your dope. First verify your parameters (is the distance from your scope to bore correct?) Then make sure you're zero is correct (1/2" at 100Y can be a big deal at long range)
Lastly...and the more likely cause....Is that your scope doesn't track true. What scope do you have? Do a tracking test to see if that's the problem.
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Re: Muzzle Velocity and dope do not match
[Re: Cattleman]
#6868982
08/26/17 01:04 AM
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Joined: Dec 2008
Posts: 41,173
J.G.
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I shot through a buddies Magneto Speed tonight to finally get some idea of my muzzle Velocity and it's got me scratching my head. I fired three rounds and it gave me a MV of 2670 and a ES of 4 and a SD of 2 out of my 6.5x47 shooting Hornady 143 ELD X over 36 grains of varget. My dope tells me I'm running around 2725ish. What's up? At how many distances did you get DOPE?
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Re: Muzzle Velocity and dope do not match
[Re: Cattleman]
#6868990
08/26/17 01:09 AM
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Joined: Feb 2013
Posts: 1,051
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100-1000 every 100 yards is what I have dope for.
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Re: Muzzle Velocity and dope do not match
[Re: Cattleman]
#6869036
08/26/17 01:42 AM
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Joined: Nov 2011
Posts: 3,639
DStroud
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Points above are good ones especially the fact that just being off of 1/2 inch at a true100 yards can give bad numbers. Also I have sighted in at a range then discovered the 100 yard range was actually 100 meters/ 109 yards
"Anyone taking up handloading necessarily plays with unknown factors and takes chances. But so does anyone who drives a car,goes to a cocktail party,eats in a restaurant,or gets married."
Jack O'Connor 1963
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Re: Muzzle Velocity and dope do not match
[Re: Cattleman]
#6869042
08/26/17 01:47 AM
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Joined: Dec 2008
Posts: 41,173
J.G.
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100-1000 every 100 yards is what I have dope for. Plug in your known velocity (from the Magneto Speed), male sure you have input the exact twist rate for your barrel. Measure, with calipers, center of scope tube to center of bolt, male sure all of those parameters are correct. Then adjust BC in an attempt to get DOPE to match the calculator.
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Re: Muzzle Velocity and dope do not match
[Re: Cattleman]
#6869276
08/26/17 12:25 PM
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Joined: Jun 2011
Posts: 33,988
Buzzsaw
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Don't ever trust any dope chart or chrono without shooting the gun at distance to confirm.
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Re: Muzzle Velocity and dope do not match
[Re: Buzzsaw]
#6869285
08/26/17 12:39 PM
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Joined: Dec 2008
Posts: 41,173
J.G.
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Don't ever trust any dope chart or chrono without shooting the gun at distance to confirm. DOPE is shooting at distance. Data On Previous Engagement Don't trust predicted corrections, via calculator without shooting at distance.
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Re: Muzzle Velocity and dope do not match
[Re: Cattleman]
#6869380
08/26/17 02:20 PM
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Joined: Apr 2010
Posts: 6,219
dee
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What bc are you running?
Velocity difference is usually noticed more inside of 500yds while bc variation is noticed out farther. Also double check scope hieght.
"A vote is like a rifle; it's usefulness depends on the character of the user" Theodore Roosevelt
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Re: Muzzle Velocity and dope do not match
[Re: Cattleman]
#6869386
08/26/17 02:24 PM
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Joined: Jun 2015
Posts: 5,923
Jgraider
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100-1000 every 100 yards is what I have dope for. If you actually shot and verified these distances, that's all the dope you need. Forget what the chrono said. Use actual shot verification and you're done.
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Re: Muzzle Velocity and dope do not match
[Re: Cattleman]
#6869417
08/26/17 02:56 PM
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Joined: Apr 2011
Posts: 991
Kevin1
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If you have covered what I said in my first post then there are other factors as well. Your MV difference is around 50fps. If you're barrel is new, after a few hundred rounds, it's very common to see a MV increase of around 50 fps. Also if you ammo is at the warmer temperature at the time of shooting it will increase MV as well.
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Re: Muzzle Velocity and dope do not match
[Re: Jgraider]
#6869455
08/26/17 03:37 PM
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Joined: Dec 2008
Posts: 41,173
J.G.
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100-1000 every 100 yards is what I have dope for. If you actually shot and verified these distances, that's all the dope you need. Forget what the chrono said. Use actual shot verification and you're done. That's all fine and good if he shoots those distances, only, and always in those environmental conditions. Once he wants to go farther, once the weather changes, and once he is shooting in a major elevation change on the planet, he needs his calculator to be trued. Which is what he is trying to do right now, for good reason.
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Re: Muzzle Velocity and dope do not match
[Re: Cattleman]
#6869637
08/26/17 08:02 PM
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Joined: Nov 2011
Posts: 3,639
DStroud
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What JG said.... it can change as the day warms and cools.
"Anyone taking up handloading necessarily plays with unknown factors and takes chances. But so does anyone who drives a car,goes to a cocktail party,eats in a restaurant,or gets married."
Jack O'Connor 1963
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Re: Muzzle Velocity and dope do not match
[Re: J.G.]
#6869646
08/26/17 08:13 PM
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Joined: Jun 2011
Posts: 33,988
Buzzsaw
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Don't ever trust any dope chart or chrono without shooting the gun at distance to confirm. DOPE is shooting at distance. Data On Previous Engagement Don't trust predicted corrections, via calculator without shooting at distance. What he said
SPACE FOR RENT
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Re: Muzzle Velocity and dope do not match
[Re: Cattleman]
#6869920
08/27/17 01:04 AM
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Joined: Feb 2013
Posts: 1,051
Cattleman
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I think scope height is my problem. My dope is good to go. I shot a match today and scored pretty good.
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Re: Muzzle Velocity and dope do not match
[Re: Cattleman]
#6870245
08/27/17 02:46 PM
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Joined: Dec 2008
Posts: 41,173
J.G.
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I think scope height is my problem. My dope is good to go. I shot a match today and scored pretty good. Good news! Ironically a guy at my station that works the shift after me, came in with the same problem yesterday. DOPE and calculator not matching up. I said "did you start over?" He didn't know what I meant. I had him go to the rifle settings and I had a look. He had his sight height at 0". I changed it to 2" as a place to start, and numbers looked way better.
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