I'm near the end of my first 400MODBB barrel in 6CM. With my last 2 (regular) barrels in 6 Creed, the barrels would slow down around 1000-1100 rounds. They would then continue to shoot well for another 500-600 rounds or so, and then either slow down more or start to throw fliers. So basically I got about 1500 good rounds out of them. My current barrel started out the same, but did not slow down until just after 1500 rounds. I now have just under 2200 rounds on it. My best groups are still tight, but my perception is that overall my groups are starting to open up a bit. And I'm seeing more vertical issues in the last couple hundred rounds, hard to say if that is the barrel or the conditions. But the new barrel material has definitely extended the useful life for this caliber. This is in a 28" barrel, with ave around 3050fps at its peak, currently running around 3020fps. This is hooting a mix of PRS style matches and our club long range matches (50 shots in an hour or so, typically 3 groups of 3 at a time in maybe 5 minutes).