260 Rem Load Data

[Da Wolf]

I built a AR10 in 260 Rem and have some Lapua 123 gr Scenar and would like to shoot it with my RL-19 powder. The only data I can find is with N550 which shoots good, but gives me high SDs and ESs. The RL-19 with ELD-Ms gives me the lowest SDs and ESs. I would like to see what the Lapua do with the RL-19. Since I can't find any stating load data for this combo any suggestions on where to start? With the N550 it is stated not to exceed 41.5 grains of powder using the Lapuas. Using the RL-19 and 130 Gr ELD-M I currently run 45 grains of powder (not quite to the max charge yet).

Thanks

 

[pabrousseau]

Sierra re19 load with 120 gr bullets is 42.2 starting and 46.2 max.
42.2gr = 2700fps
44.2gr = 2800
46.2gr = 2900
This is with 24 inch barrel. I'd use this data as both bullets are cup and core and start low.
Seems difficult to read pressure signs in the ar rifles . Chronograph works.
I'd figure 30fps velocity loss per inch of barrel.