7mm Rem Mag 7977

Kmccord

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Joined
Nov 30, 2016
Messages
783
Location
Reilly Springs, TX
How are you weighing your powder? If using an Electronic powder dispenser, you may have a drift and throw a little more, I use a balance beam scale to measure against it. Also, what kind of Chronograph? If an optical one, it depends on time of day with sunlight, I have to watch the shade creep over mine when shooting in the evening, it will throw a bad reading once the shadow takes over and then stops reading.
 

wird06

Member
Joined
Nov 23, 2020
Messages
17
Location
North Carolina
How are you weighing your powder? If using an Electronic powder dispenser, you may have a drift and throw a little more, I use a balance beam scale to measure against it. Also, what kind of Chronograph? If an optical one, it depends on time of day with sunlight, I have to watch the shade creep over mine when shooting in the evening, it will throw a bad reading once the shadow takes over and then stops reading.
I use a Caldwell chronograph, it did change from sunny to overcast as it was late in the day. I use a hornady powder dispenser.
 

Canhunter35

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Joined
Jun 13, 2017
Messages
2,954
Here are my average velocities, I don't know how the explan the average up and down at 68.6 @ 69.8
68.0- 2905
68.3- 2931
68.6- 2909
68.9- 2939
69.2- 2984
69.5- 2981
69.8- 2970
Try loading 69.5 and adjusting seating depth to tighten ur group up. Ideally, that flat spot will also group on the target, but it doesn’t always work that way, thus u need a target to confirm ur chrome readings
 

wird06

Member
Joined
Nov 23, 2020
Messages
17
Location
North Carolina
Try loading 69.5 and adjusting seating depth to tighten ur group up. Ideally, that flat spot will also group on the target, but it doesn’t always work that way, thus u need a target to confirm ur chrome readings
Thank you. I have seen that the ELD bullets like a large jump, I thought about doing the setting depth from 0.010 to 0.040 in 0.010 increments
 

Jud96

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Joined
Jun 30, 2013
Messages
2,908
Location
Michigan
Yeah u may need to keep going, .05” is a good spot to test elds at.
I agree with this. All three 7mm Rem Mags I worked with this year liked a lot of jump with 162gr ELD-Ms. I know my Dad’s was .050 off, one of my buddy’s rifles liked .060 off, and my cousin’s rifle was seated a little overall book length so like 0.080-0.100 jump.
 

wird06

Member
Joined
Nov 23, 2020
Messages
17
Location
North Carolina
A little update. I was able to sneak out of the house for do my seating depth test. Here are the results, I did screw up and forget my cheap loads I use for cold bore so that kinda messed up my -0.010 test. I'm thinking of trying the -0.010 and -0.050 depths again.

Now my shooting platform is the bed of my truck so I feel that has a little play in this.
 

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Jud96

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Joined
Jun 30, 2013
Messages
2,908
Location
Michigan
A little update. I was able to sneak out of the house for do my seating depth test. Here are the results, I did screw up and forget my cheap loads I use for cold bore so that kinda messed up my -0.010 test. I'm thinking of trying the -0.010 and -0.050 depths again.

Now my shooting platform is the bed of my truck so I feel that has a little play in this.
By looking at that, .020 off is a nice triangular shaped group. I might retry -.010 but I would really try .015, .020, and .025 off. Seeing a triangle shaped group is a sign you’re either on the mark or very close.
 

wird06

Member
Joined
Nov 23, 2020
Messages
17
Location
North Carolina
By looking at that, .020 off is a nice triangular shaped group. I might retry -.010 but I would really try .015, .020, and .025 off. Seeing a triangle shaped group is a sign you’re either on the mark or very close.
Awesome thank you. Yeah I wasn't really sure what to do. I wished I remember to bring my cheap loads for my cold bore to see what the 0.010 group was .
 

Kmccord

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Joined
Nov 30, 2016
Messages
783
Location
Reilly Springs, TX
Awesome thank you. Yeah I wasn't really sure what to do. I wished I remember to bring my cheap loads for my cold bore to see what the 0.010 group was .
Run the test again and see if the same results are duplicated, if you have a Chronograph, use it at the same time to see where you are on ES/SD. I had a great group in my 7Mag, but the ES/SD was repeating in double digits, the next best group repeated same low ES/SD, I went with the second best group do to the ES/SD.
 

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