Velocities

[gixer1]

I have been developing a load for a new rifle (6.5CM) with 140gr Sierra Gamekings and have worked up from 41.5gr to 46.5gr of RS 62 and have tried various seating depths at these charge weights.

I am finding that the most accurate is 42gr and a .0040” jump to the lands however this is chronoing at around 2560fps MV. Which means at 250yards it would be at around 2300fps.

I have another CM that I tend to run around 2850-2900 fps. However when I up the charge in this rifle it seems to open the grouping up slightly - still fine for minute of deer but not as accurate as the 42gr load.

I found some test data which suggests gamekings work best between 2100-2700fps here - Minimum impact velocity for Gamekings? - 24hourcampfire

So what are peoples opinions on velocities? Is it an issue to run it at this? When is “slow” too slow? And when is “fast” too fast?

Regards.
Gixer

 

[HandB]

I would go with 42gr load as a moderately fast bullet that hits precisely where it is supposed to every time is more valuable than a fast one that misses. I tend to run all my rifles at moderate velocities except my .222 which likes hot loadings and has such mild recoil it is still accurate even at the upper limits of the loading scale. Funnily enough the PRS experts across the pond are converging on moderate velocities as being better than high velocities:

 

[NullMac]

I have another CM that I tend to run around 2850-2900 fps. However when I up the charge in this rifle it seems to open the grouping up slightly - still fine for minute of deer but not as accurate as the 42gr load

…for that seating depth

 

[gixer1]

…for that seating depth

No, tried various seating depths on all charges. From touching the lands back in .0010 increments to a .0050 jump.