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#6868960 - 08/25/17 07:51 PM Muzzle Velocity and dope do not match
Cattleman Online   content
Tracker

Registered: 02/09/13
Posts: 801
Loc: Palo Pinto county
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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#6868977 - 08/25/17 07:59 PM Re: Muzzle Velocity and dope do not match [Re: Cattleman]
Kevin1 Online   content
Tracker

Registered: 04/06/11
Posts: 595
Loc: Allen Tx
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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#6868982 - 08/25/17 08:04 PM Re: Muzzle Velocity and dope do not match [Re: Cattleman]
FiremanJG Online   content
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Registered: 12/16/08
Posts: 21802
Loc: Wolfe City, TX
Originally Posted By: Cattleman
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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#6868990 - 08/25/17 08:09 PM Re: Muzzle Velocity and dope do not match [Re: Cattleman]
Cattleman Online   content
Tracker

Registered: 02/09/13
Posts: 801
Loc: Palo Pinto county
100-1000 every 100 yards is what I have dope for.

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#6869036 - 08/25/17 08:42 PM Re: Muzzle Velocity and dope do not match [Re: Cattleman]
DStroud Offline
Pro Tracker

Registered: 11/02/11
Posts: 1586
Loc: Waco
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

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#6869042 - 08/25/17 08:47 PM Re: Muzzle Velocity and dope do not match [Re: Cattleman]
FiremanJG Online   content
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Registered: 12/16/08
Posts: 21802
Loc: Wolfe City, TX
Originally Posted By: Cattleman
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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#6869276 - 08/26/17 07:25 AM Re: Muzzle Velocity and dope do not match [Re: Cattleman]
Buzzsaw Offline
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Registered: 06/29/11
Posts: 10300
Loc: Frisco, Texas
Don't ever trust any dope chart or chrono without shooting the gun at distance to confirm.
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#6869285 - 08/26/17 07:39 AM Re: Muzzle Velocity and dope do not match [Re: Buzzsaw]
FiremanJG Online   content
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Registered: 12/16/08
Posts: 21802
Loc: Wolfe City, TX
Originally Posted By: Buzzsaw
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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#6869380 - 08/26/17 09:20 AM Re: Muzzle Velocity and dope do not match [Re: Cattleman]
dee Offline
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Registered: 04/10/10
Posts: 5062
Loc: Red River way
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.
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#6869386 - 08/26/17 09:24 AM Re: Muzzle Velocity and dope do not match [Re: Cattleman]
Jgraider Offline
Tracker

Registered: 06/13/15
Posts: 644
Loc: West Texas
Originally Posted By: Cattleman
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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#6869417 - 08/26/17 09:56 AM Re: Muzzle Velocity and dope do not match [Re: Cattleman]
Kevin1 Online   content
Tracker

Registered: 04/06/11
Posts: 595
Loc: Allen Tx
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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#6869455 - 08/26/17 10:37 AM Re: Muzzle Velocity and dope do not match [Re: Jgraider]
FiremanJG Online   content
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Registered: 12/16/08
Posts: 21802
Loc: Wolfe City, TX
Originally Posted By: Jgraider
Originally Posted By: Cattleman
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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#6869637 - 08/26/17 03:02 PM Re: Muzzle Velocity and dope do not match [Re: Cattleman]
DStroud Offline
Pro Tracker

Registered: 11/02/11
Posts: 1586
Loc: Waco
What JG said.... it can change as the day warms and cools.

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#6869646 - 08/26/17 03:13 PM Re: Muzzle Velocity and dope do not match [Re: FiremanJG]
Buzzsaw Offline
THF Celebrity

Registered: 06/29/11
Posts: 10300
Loc: Frisco, Texas
Originally Posted By: FiremanJG
Originally Posted By: Buzzsaw
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
_________________________
"I ain't here for a long time, I'm here for a good time"
King George Strait



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#6869920 - 08/26/17 08:04 PM Re: Muzzle Velocity and dope do not match [Re: Cattleman]
Cattleman Online   content
Tracker

Registered: 02/09/13
Posts: 801
Loc: Palo Pinto county
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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