I was once loading some 95gr .380 pretty stiffly and when i went to the range to chrono them they were close to 1000fps but boy did they kick in my Colt Mustang. I figured I better back off the charge a little and when I went back to my bench I discovered I was picking out of the 122gr Berry's box, not the 95gr Remington FMJ next to it. I have no idea what kind of pressure was absorbed by that little Mustang but I was lucky that day.

I am leaning toward the OAL being too short driving up pressure but any chance you could have loaded a heavier bullet than 125?