Paul,
You're NOT looking for max velocity with a DR.
You look for the closest gouping possible. Just note the velocity so that you can dulicate that later on with other lots of the powder and components. IMO The RL-15 varies some between the different batches and you need to know what works with this lot number so it can be duplicated later on.
The max load has already been run thru that rifle with the proof loads. You don't want to go there again!
If these are loads that Sam Rose gave you then you're good to go! I looked at Wrights book for the 470 and it's interesting that he doesn't show the RL-15.
Mike, I did not intend for my post to suggest I was seeking max velocity.
I am simply using velocities as a general guide in the load development process.
This gun is a 500, not a 470.
And yes Graeme only lists one load for R15 in the .500 but two good freinds of mine who were involve with extensive testing of the .500 cartridge found a number of useful and efficient loads using R15 and lacking any need for fillers or wads.
The rifle was factory regulated with a 570gn slug and I am trying to tune in 475gn slugs to the same point of aim.
At this point loads tested with 100gns of R15 are still nearly an inch low of point of aim and the composite of the two barrels is close to three inches apart.
The loads Sam gave me consisted of 535gn and 510gn slugs and those loads were regulated for a Sabatti rifle.
These loads contained up to 100gns of R15 for the 535gn.
Everybody has agreed that to bring the barrel groups together more, and slightly higher, back to the point of aim, with a lighter slug, it was safe to assume a slightly higher charge that would increase vels slightly and brings the barrels closer together.
I am going a grain up at a time, looking for any signs as I go.
Appreciate the warnings.
Paul.