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.
