.308 Load help required

[etiennepretor]

Hi,
I am posting my loads shot at 200m (219 Yards) - This is the distance I Like to develop.
I am a bit baffled, With 178gr Hornady I shoot the same distance a tight group - shots cutting @ 2602fps (Indicated as Test on photo)
Rifle = Sig Saur 100 Field Shoot.
Twist = 1:11
Barrel = 24"Bull Barrel with a Muzzle Break,
178gr ELD-X load (VihtaVuori 41.5gr N540) COL.71mm(2.795 Inches), CCI200 Primers, Lapua Cases

New:
175gr Lapua OTM MaxRT Bullets
VihtaVuori N540 (Grains indicated on Picture)
CCI200 Primers
Speed indicated on pictures.

Please advice on the way forward....
Was hoping for 2600fps, but nodes are opening up.

I want to shoot more acuratly at 1mile.
The ELD-X does it, but not that great at that distance

 

[ShtrRdy]

I would try more, higher, powder charge weight in 0.3 grain steps. Up to 2700 fps to see if there is a better "sweet spot".

 

[etiennepretor]

Thanks for reply - will give it another try.

 

[ShtrRdy]

When you do the next series of powder charge weight I would look for groups that impact in the same area on target. Then I would try different seating depths.

Do you have much wind blowing when you are shooting at 200 m?

 

[etiennepretor]

Thanks for all the help everyone.
Settled on COL.71mm
42gr N540 @ 2612fps.

Reshow a string from in .3 grs from below 40gr. 41.9 and 42.2 is the tightest, going with 42gr.

Cheers

 

[Skeptic1]

Zero at 100 yds for load development. After load development move your zero out further if you would like.
Further distance allows for more human error to enter the equation. You dont want that when developing your load.

 

[Rocketmandb]

Some general notes on load development with different bullets:

- Just because you have a good grouping with one bullet at 2600fps (or any velocity), it does not mean that velocity will work for all bullets - even bullets of same/similar weights. There is a myriad of variables that will impact your grouping.

- Velocity by itself is not the only determining factor of group size. It will play a role, but I've found that seating depth plays a bigger one, especially with non-hybrid ogive bullets. I like to use the load that gives the best combination of SDs and at least a decent group size, then tune in with seating depth.

- As others have said, doing groups at 100m (or yards) is better, as you minimize other variables. That said, you've got some groups at 200 yards that you likely can work with by tuning to seating depth. The one shot out left of the 42gr looks like a pull. The other three are likely just above .5 MOA. You could try more at that charge weight then try to bring in with seating depth. That said, if your SDs are poor, then your desire of taking a 308 to a mile will be an exercise in frustration.

Recommendation:

- Redo groups either (3 or 5-shots per) and measure velocities/SDs
- Do the groups at 100m
- Look at group size, but concentrate on SDs
- Find the best few combos of SD/group size/desired velocity
- Run more rounds at those velocities to validate or invalidate each
- Play with seating depth