Nice group

[Racalman]

I shot this while load testing .308 at 100yards on Short Siberia on Sunday. Rifle on bipod, no bags.

Should I settle for that or start adjusting the bullet jump?

[Triffid]

Nice as a starter, but you need to fire a few more shots. Three-round groups are fine for zeroing, but you need 5 to 10 shot groups to really assess how good a combination is.
Triffid

[Racalman]

Yes, understood.

[ovenpaa]

I agree, shoot a few 5 shot groups first before considering any potential changes to your load. The part to watch is the vertical height as it is more an indication of the accuracy than the horizontal which is impacted by wind changes.

[Racalman]

One could experiment endlessly but the cost of bullets and powder, not to mention barrel life, can be significant.

I shoot three round groups of loads increasing in 0.5gn increments to get me in the right ballpark. It took 18 shots to get that half MOA group.

I could fine tune it with 0.2gn powder increments, bullet jump in 0.015" increments, chronograph ES etc. but is it worth it? If I can repeat 0.5MOA off a bipod consistently then I'll be happy.

[WelshShooter]

In my opinion, the accuracy of a load should be determined by the largest grouping, not the smallest. If you shoot ten five-shot group, is it acceptable to have one 0.25" group and nine >1.0" groups, or is it better to have ten 0.5" groups?

Yes, it's understandable to shoot 3-5 shot groups during load development to give you an indicator of a decent powder load but repeatability is key. I've repeated load development a couple of times to find that what shot great the first time was not great the second or third time. I did successive loading of the "second best" group from the first trial and found this to be more consistent and repeatable. Something to bear in mind.

[Racalman]

In my opinion, the accuracy of a load should be determined by the largest grouping, not the smallest. If you shoot ten five-shot group, is it acceptable to have one 0.25" group and nine >1.0" groups, or is it better to have ten 0.5" groups?

Fair point. I will certainly be repeating the exercise to see if it was a fluke (and probably use bags next time), but with holidays and other stuff coming up it will not be for a while yet.