It's 950 m/sec. Had a tiny suprise last night cleaning the barrel.
The barrel is only 18,5" long. Didn't really pay attention as we were building it.
Short barrel shooting an inferior Bc 0,4 bullet but still first-shot hits at the 0.2-0.4 MIL sized targets I've shot out to ranges of 750 meters (825 plus yards).
All in all I value my hearing a lot more than the marginal increase in killing window a longer barrel will give me, so next barrel will be at similar lenght.