Looking for a general idea of velocity with Benchmark

[Harpoon1]

Hey all, so I've been playing with my PSA 20" Grendel lately, and found a load that is giving me insane accuracy, but I dont have a chrono to check it, and I've got no idea what kind of velocity to expect.

I've been loading 27.2 grains of Benchmark behind a 123 SST, and according to Hodgdon's website and my Lee manual I should be getting around 2400fps, but factory ammo like the Black and Custom come in around 2550-2600fps. Is factory ammo that hot, or are the numbers wrong on my reloading manuals?

I would suppose with a 20” barrel you could subtract somewhere around -100 FPS from my data, all things considered.

http://www.65grendel.com/forum/showthrea...t=Harpoon1