My load for my 55 cordite Jeffery 400 3" has turned out to be 67.5 grs of 4064 with 400 gr Woodleigh Softs, Fed 215s and 1.5grs of Dacron fill in Bell Brass. It shoots into an inch at 50 yds right on top of the bead at 2050fps.

With Hornady 300 gr .411 bullets I lower the charge to 66 grs of 4064 and get a 2120fps load that regulates well.

I tried the standard 4831 and Rel 15 loads but could not get the same regulation. It's funny how few guns I've got to shoot well with Rel 15. I've had a few including my 416 Hoffman that love 4064. It's probably because I'm a lefty

No doubt each double is a story of it's own.