Load decision. Smaller SD or smaller groups

[Raufoss]

Need some help guys.
So if you had the choice with the following what would you choose and why?

1st :
30.92gr
New Alpha 6 Dasher OCD brass untouched
N150
109gr berger
Average : 2819 fps
SD: 4 fps
ES: 10 fps
Shot number one was my clean cold bore so I’m not stress about the group.

2nd :
31gr
New Alpha OCD 6 Dasher brass - Sinclair expander
N150
109gr Berger
Average : 2819 fps
SD: 7 fps
ES: 16 fps
Shot number 5 is a potential flyer or maybe part of the composite group . All I know is that I remember telling myself to not screw that last shot so potentially it’s a flyer looking at the group..

what do you guys think? Average speed for both charge is obviously the same but should I choose the lowest SD/ES even is the difference is small or choose the potentially smaller group?

I don’t have the time to push development more as I have a match in 3 days.

 

[nn8734]

Can’t truely accurately answer this question at the moment as SD/ES numbers should only be considered actionable if the figures were gathered over a 30+ round sample of the same load recipe.

But if we can assume that five shot group in the second image (disregarding the flyer - likely shooter error) is representative of how the rifle / shooter will typically perform over say 6 random groups of 5 rounds each (6x5) of that ammo/Load recipe, and that Sd/Es holds up and shooter error isn’t a factor in either group, I’d go with the load used to make the group in the second image.

the vertical stringing in group 1 may also be more shooter than load. I’d retest both if at all possible before making a final decision. If that’s not possible, and you’re “under the gun” to make a decision solely on this info, I’d roll with group 2. If it falls flat on its face you know you have more work to do.

lots of caveats, too many to list…

 

[Newbie2020]

I doubt they’re truly different.

Shoot 20 rd groups of each and see what happens to sd/es and group size.

0.685 moa is plenty good to hit 2 moa targets

 

[Old_Longhair]

IMO, good ES/SD numbers are important for longer ranges. A lot of loads can work reasonably well @ 100yds, but consistency becomes much more necessary if you want to do well beyond that.

 

[nn8734]

Just curious, why did you wait until 3 days before a match to start load rtde?

 

[Raufoss]

Can’t truely accurately answer this question at the moment as SD/ES numbers should only be considered actionable if the figures were gathered over a 30+ round sample of the same load recipe.

But if we can assume that five shot group in the second image (disregarding the flyer - likely shooter error) is representative of how the rifle / shooter will typically perform over say 6 random groups of 5 rounds each (6x5) of that ammo/Load recipe, and that Sd/Es holds up and shooter error isn’t a factor in either group, I’d go with the load used to make the group in the second image.

the vertical stringing in group 1 may also be more shooter than load. I’d retest both if at all possible before making a final decision. If that’s not possible, and you’re “under the gun” to make a decision solely on this info, I’d roll with group 2. If it falls flat on its face you know you have more work to do.

lots of caveats, too many to list…

totally agree, I wish I would have the time to test a larger sample but I won’t be able to make it before Wednesday for my flight.

I doubt they’re truly different.

Shoot 20 rd groups of each and see what happens to sd/es and group size.

0.685 moa is plenty good to hit 2 moa targets

Make a lot of sense but can’t make it back to the range before leaving . I need to load tomorrow.

 

[Newbie2020]

IMO, good ES/SD numbers are important for longer ranges. A lot of loads can work reasonably well @ 100yds, but consistency becomes much more necessary if you want to do well beyond that.

This. But we won’t see the effect of sd/es on group size at 100 yds; only at longer ranges

 

[Raufoss]

Just curious, why did you wait until 3 days before a match to start load rtde?

Because I don’t have much time for me and I just got the new barrel Friday and I tested the old load Sunday and it was of a little . The old load in the new OCD is a little of

previously I was running 30.97 with non OCD brass at 2818 fps.

I know I’m in my node for the speed but there is a small difference with the brass.

The same load in virgin OCD brass is 15-20 fps faster so that why I’m playing with untouched brass and expanded neck to see what to choose. The new unfired OCD have a tighter neck tension.

virgin pre-OCD 30.97gr are 2830
Virgin pre-OCD 30.97gr + expander are 2813

virgin OCD 30.92gr are back to 2819
Virgin OCD 31gr + expander are back to 2819

 

[nn8734]

Because I don’t have much time for me and I just got the new barrel Friday and I tested the old load Sunday and it was of a little . The old load in the new OCD is a little of

previously I was running 30.97 with non OCD brass at 2818 fps.

I know I’m in my node for the speed but there is a small difference with the brass.

The same load in virgin OCD brass is 15-20 fps faster so that why I’m playing with untouched brass and expanded neck to see what to choose. The new unfired OCD have a tighter neck tension.

Makes sense, it is what it is…Given how you reacted to my question I figured you were going to plead the 5th on it, haha.

Good luck with the match

 

[Newbie2020]

Good ammo (brass prep, powder drop, consistent neck tension) will shoot sub moa in a good barrel.

Seating depth can tune group size by 0.1-0.2 but not enough to win or lose a PRS-type match

 

[Raufoss]

Makes sense, it is what it is…Given how you reacted to my question I figured you were going to plead the 5th on it, haha.

Good luck with the match

Haha thx

 

[Doom]

Your velocity data is not worth much other than to say your loading is very consistent. The low SD is pushing the limits of your chronograph repeatability and the low round count doesn't give you a lot of certainty in the SD numbers anyway. The targets can't read the chronograph numbers but it sure seems happy with with the 7SD load.

 

[Dthomas3523]

For the time being, if you think that “flyer” was you, go with the smaller group.

With the limited data you have, neither is bad on the chrono side. And neither groups are large enough to lose the match. But, take the smaller group as it *might* pick up an impact on a small kyl if you’re in contention for the top spots.

Or flip a coin. With the provided data, neither will be detrimental.

 

[Dthomas3523]

Also, keep in mind for future load development. If you’re a proponent of OCW and/or positive compensation load development, SD/ES matter far less.