I did this yesterday, 10 rounds per gun, temp outside was 47 degrees. G43 averaged 915 fps, the 26 and 19 averaged 938-956 fps and the 34 averaged 994 fps. The fastest round was from the 34 and was 1009 fps. Your mileage may vary, i dont know how slow an hst will still expand but there isnt a huge difference in velocity however there is a difference. At 25 yards it probably matters more, at 50 yards would any reliably expand? I dont know. This info came from a $100 caldwell chrono. I rounded off some of the calculations but the above numbers were not rounded up if they were rounded off. My glock 19C tends to shoot velocities more similar to the 26 instead of a standard 19 but i didnt test it yesterday. I have 124 +p ill test today and post those numbers. I assume the spreads will be greater