Just picked up a Glock 31 (full size .357 Sig). Took it to the Dept. range to run some ammo through it and I asked the Rangemaster to chronograph muzzle velocity. He used the Dept's Oehler Model 35 at 4 feet from the muzzle (PD standard).
Below is the average velocities of different loads (All are 50 round averages):
Speer GDHP 125-grain---1435 fps
Hornady XTP 124-grain--1430 fps
Cor-Bon JHP 125-grain---1465 fps
250 rounds total---no issues. Feeding is extremely reliable due to the bottlenecked cartridges.