Lapua Max Range Target

[KRG]

Try Vihtavuori N555 40gr and do not load it more than 72mm in lenght, not even how much you would like to extend the COL.
Try that, iF it does not work, i would say it is the barrel twist you got might be the issue.
That Max Range 144gr weight might be on the edge of 1/8" and 1/7,5", not liking that fast twist.
If you dont find it working, then there is no point to waist no more time and effort for it.
Also test the 139gr Scenar and Scenar-L 136 with 70mm COL, DO not take the pill to the lands.
If the barrel work, it will do one hole groups.
If not, change it in to a 1/8".
If the bullet weight that you mostly use is 120 - 144 gr.

[Nor0]

Bjorn, you have normal primer? Have to use magnum for these powders

[KRG]

I use Magtech 7 1/2, CCI450 and Federal GM 205M primers.

[bjorn]

Bjorn, you have normal primer? Have to use magnum for these powders

All testing done with Lapua SRP and Federal GM205M primers seated to a light crush.
ES and SD number are good (10 shots ES under 30FPS and SD under 10FPS or better).

Do not know when I will be able to hit the range again, but I loaded some Lapua Scenar-L 136gr shorter as you proposed.
Spent all the 139gr Scenars, will need to order some more.
In the mean time I will test Berger LRHT 144gr a bit more and Berger LRBT 140gr. The LRHT 144gr gives promise.

[KRG]

Please, do test the Scenar-L 136gr and Max Range with these COL.
Scenar-L 70mm, try with 42,5gr with VV Triple-5, this load works well on my Krieger and Strasser 6.5 CM.
Max Range 72mm and 40gr of Triple-5.
And from the clean barrel, copper is not issue, but remove all the carbon, that is the enemy, not the copper.
Shoot couple of foulers to the barrel, so that it get´s some copper in the bore.
Then try to shoot the groups.
If still no working, then it just wont work.
Good luck.