here is a test target I shot with my 110BA, using Hornady brass...
You can see that I got a flyer at 100 yards with 92 grains of Retumbo and the Sierra 300 Matchkings.
Lapua has about 97.5% the capacity of the Hornady, and so if you find an OCW node with Hornady, you'd expect to see that same node, using Lapua brass, with about 97.5% of the powder charge you used in the Hornady...
If you're using Lapua brass (which it looks like you may well be), then you'd have a node at around 89 grains... and you'd have an unstable node at around 90 to 91 grains, which is what you're reporting (flyers being common)...
Back the powder charge down to 89 grains of Retumbo and see how they do at 300 yards...
Dan