Best Powder for Accuracy in 9MM?

[Thor]

Two things concern me here. If he is getting reliable working of the action with the lower load, putting the higher load through it will undoubtably stress the toggles when they strike the cam surfaces of the ears. I would not shoot the hotter load in his gun unless it had a stronger spring. I think each Luger should have a load or too that it likes and fires reliably and doesnt bang the heck out of it. When I get Lugers in to the shop that have a weak spring (I feel it when I open the action) a lot of times the cam surfaces are peened baddly indicating too hot a load was fired for the weak spring that was in it. Harry Dennis sent me a early Luger, with that flat spring that was very weak, the Luger also had a cracked toggle from firing it with the weak spring. I shoot 5.7 grs of Unique behind a 124 FMJ but only in guns that have a spring tension close to factory specs. I also shoot 8.0 grs of blue dot behind a 124 in Artillerys when the first lighter load doesnt function the action with enough ejection power. After I put the hotter load in there with the slower burning powder, they always work like a champ. I DONT recomment this load for Artillerys that have had their main spring weaken to function with the standard American Loadings, that would be a big mistake.