N570 in a 6.5 PRC

Hard rock

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Dec 20, 2020
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539
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Tomball Texas 77377
Well the case length was under the trim like by .10” and it’s brand new brass and I do understand that it will grow I just wasn’t sure where to start for bullet seating depth so I did the oal of the 2.955 for case and bullet to start sense I have not got any factory loads for break in
Thats exactly the oal I load with a .145 throat with the 123 gr absolute hammers from what I have read they started out with .130 throating which would put you into the lands with a factory 2.950 oal on a 143 gr hornady but cahanged it too a .180 throat as a standard throating if thats what you have your probally close too . 050 from the lands depending on your bullet and throat of course
 

ApollosMagnum

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Feb 15, 2021
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Tennessee
Well the case length was under the trim like by .10” and it’s brand new brass and I do understand that it will grow I just wasn’t sure where to start for bullet seating depth so I did the oal of the 2.955 for case and bullet to start sense I have not got any factory loads for break in

if you are limited to 2.955 by magazine or action length then that is a good place to start (edit: with most bullets. Search for load data for your specific bullet.) . If you aren’t, there are other ways to find where the bullet touches the lands such as using a fired case and denting the neck slightly so it grips the bullet a little, color the bullet with a sharpie and barely insert the bullet into the brass and chamber it with the bolt closed. The lands will push the bullet further into the brass and the brass will leave a mark on the bullet.

Either way, for break in it doesn’t matter and you won’t sacrifice that much seating them to magazine length.
 

bowhunter1287

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Feb 3, 2015
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220
Well that is about all I can fit into magazine and I have read the sharpie with a fired case but don’t have one yet lol and these are with the hornady 143 eld x as they were cheaper to break in with instead of the 153 a tips that I have to shoot out of it.
 

coyotezapper

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Sep 26, 2009
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988
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Central Utah
I know this is an old thread, but I have some data to help anyone looking into N570 in 6.5 PRC.

A couple disclaimers:
1. I used Quickload to get some starting loads, and the velocities I am getting are around 100fps more than Quickload is estimating and I can't seem to find the discrepency in the data I input.
2. My bolt doesn't have a very tight fit between the firing pin and the hole, so I get cratering on just about everything, that being said, the severity of cratering did not noticeably change across any of these tests.

26" Helix 6 Carbon barrel
.188 Freebore
Fired case holds ~69.1gr H20
CCI BR2 primers
Hornady Brass trimmed to 2.015"
Neck tension about .0015"
Velocities measured using Magnetospeed v3

One round of each powder charge.
All of these are compressed loads.

156 Berger EOL loaded ~3.080" COAL (.010" off lands for me)

60.5gr 3013 fps
61.0gr 3013 fps
61.5gr 3066 fps (noticed I needed to tug the bolt to extract here for some reason)
62.0gr 3078 fps
62.5gr 3057 fps
63.0gr 3118 fps
63.5gr 3176 fps (slightly stiff bolt lift and slight ejector mark, decided to stop here)

153 Hornady A-Tip loaded .010" off lands

60.0gr 2964 fps
60.5gr 3042 fps
61.0gr 3053 fps
61.5gr 3098 fps (slightly difficult extraction)
62.0gr 3135 fps (slight ejector mark, decided to stop here)

145 Barnes Match Burner .010" off lands

61.0gr 3080 fps
61.5gr 3095 fps
62.0gr 3110 fps
62.5gr 3142 fps
63.0gr 3154 fps
63.5gr 3200 fps
64.0gr 3219 fps (very slightly heavy bolt lift)
64.5gr 3271fps (stiff extraction, but bolt lift was fine)
65.0gr 3292fps (all good here)
65.5gr Chrono error (no bolt lift/extraction issues, but might have had a slight ejector mark, this was once fired brass and I forgot to check it beforehand)
I didn't have any more for this and honestly it was tedious enough getting this much powder stuffed in the case.

I plan to revisit some of these potential nodes with 3-5 shot groups to look for best SD and then I'll play with seating depth.

Honestly these are crazy high speeds in my opinion so I don't know if I just have a fast barrel or if my pressures are much higher than I think. I'll probably shoot for around 3000-3050 on the 156 and 153, and 3100-3150 on the 145. Can't complain about that.

To get QL to match your actual data adjust temp and powder burn rate factor to match actual velocity.
 
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