I don't have a chrono, but based on penetration into wood, 130 is the point of diminishing returns (and my recoil limit). I'm sure the 400 grain bullet allows more powder to burn. Also, I size the lead to be a tight fit which acts somewhat like a cartridge crimp - JMHO.
I have a 4/12/21 article from Woods n Water - which was recently removed from the website - where Jim Hammond tested Pyrodex loads in a V1 pistol and MV continued increasing all the way to 150 grains(Volume) RS. He got 250 grain sabot bullets over 2000 fps, but said recoil became unmanageable beyond 1800 fps.
My load pushes the muzzle vertical and twists the gun almost 45 degrees. That's how the hammer and trigger guard hit my knuckles . My hand and was numb from the first two shots, and I didn't get a proper hold on the third.
I'd love to see what this load would do from a V2 rifle.