Thread: 7 PRC MK V Weatherby load development

The Mk 5's are well known for having lots of freebore. Think from memory the jump I settled on was 40thou which shoot inch to inch and a half on a good day at 200 yds.

Range report shows promise, but velocity was still a bit low.
68gn shot an average of 2798fps with an SD of 25.4
69gn shot an average of 2861fps with an SD of 11.
Both had acceptable accuracy but I've come home and loaded up 70gn to see if I can squeeze a few more fps.
Max pressure indicates velocity of 2989 fps and I'm not over that yet, at 70gn I think I won't get much more powder in there without compressing and I'm not keen on doing that.
Hopefully the accuracy stays good or improves.
Sorry no grouping pics as I left them at the range, will be sure to take some group pics next trip.
They were only 5 round groups so not much in the way of data (I was after all just checking velocity).

70.8 of 2225 but with the 175eldx check at 500M today but only fired 2 shots elevation was bang on

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Originally Posted by 25/08 IMP

70.8 of 2225 but with the 175eldx check at 500M today but only fired 2 shots elevation was bang on

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More powder, lighter projectiles and still slower
What brass you using ? I'm using Norma.
I also figured out I wasn't actually bumping my shoulders back when I set up the sizing die, so I sorted that now with a 2 thou sholder bump. I had 1 round of my velocity test loads that gave slight resistance closing the bolt (checked at the time and projectile wasn't bring jammed into the lands)
Got home and checked fired case vs sized case and their was no difference

I'm using Peterson brass but also my barrel is just under 21 " I have just started a new tub of powder and it just under 2900fps same charge.

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Originally Posted by 25/08 IMP

I'm using Peterson brass but also my barrel is just under 21 " I have just started a new tub of powder and it just under 2900fps same charge.

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Very nice, that does explain the velocity to powder ratio too. Can I ask what your C.O.A.L is ?
I'm looking forward to shooting a larger sample to see what it will do

Originally Posted by dannyb

Very nice, that does explain the velocity to powder ratio too. Can I ask what your C.O.A.L is ?
I'm looking forward to shooting a larger sample to see what it will do

I'll have to check but it's at Tikka mag length which is about 40thou off from jam.

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Watching with interest as a 280AI fanboy Danny!!