Man is this 700mm barrel something else. wound up doing a double port mod on my new Crown's pellet probe, and elongated the brass TP. I threw in the Crown hammer kit that I modified, and with .217 30gr slugs out of my new 700mm slug liner, I clocked them at 970fps at 180 bar.
As for the bad news.. I'm pretty sure my shorty barrel is already toast! I cleaned the barrel out using Ballistol, a good rod, and some patches. I wanted to run some pellets over my chronograph last night out of the shorty first and foremost. The first shot was fine, the second one was a little slow - checked my air pressure, which was fine.. figured I'd give the reg a little longer for the next shot, and the third sounded like my valve wasn't opening. I knew something was wrong - checked the pressure, it was fine. I took the barrel off knowing that the pellet (RD monster) was still in the bore. Sure enough, it was in there a little skewed. I wound up using a wooden dowel to push it back out through the breech side.
Longer version short, I separated the brass TP piece from the stainless piece, and I found a compacted lead ring sitting in the stainless part on the breech side. I don't exactly know what happened, the only thing that I can think of was the liner moved forward slightly when I did the initial barrel cleaning.
This morning, I tried to push a 15gr JSB through and it was really right about 7/8" in. I contacted FX, they patched me through directly to Ernest who arranged for me to send the barrel in. Turnaround should be 1-2 weeks once they receive it, so I guess I'll have to wait before I can test the short barrel!