[Colt-SL]

Great detail Malysh. I'm presuming that the figures were taken consecutively and as pressures slightly rose, so did each subsequent velocity number. Any leading in the barrel with those bullets at those velocities? Super good job!!

 

[Colt-SL]

I am much more of a plain shooter and an accumulator of guns than I am versed about ballistics. Why does pressure rise after a few shots?

They don't always. The only time I noticed consistent increases while chronographing handguns was with lead bullets in the 900-900+ fps range. Unburnt powder fouling and slight leading on the inside of the barrel seemed to cause slight pressure increases and higher velocities. It made me wonder here with velocities under that figure. Perhaps someone more knowledgeable can shed some light on this.