[bbbean]

I March, I chrono'd Atlanta Arms 230 FMJ and 185 JHP in my Ed Brown Kobra on a 48 degree day at PFs (10 round averages) of 163 and 169. Today, with temps around 70, I chrono'd them at 158 and 163 (16 round averages). I'm pretty sure I haven't worn my barrel enough to produce that kind of change, and it seems like the rounds should have sped up with the temp change. The only change I can think of that would explain the slowdown is that I've run a few hundred rounds through the gun since the last time I cleaned it

Would you expect a PF change of 6 with a dirty gun?

[P.Pres]

If your barrel could get that dirty (obstructed) it would have the opposite effect as
the pressure would be higher. Different light conditions Time of day, weather) can
effect the reading on the crono. Some powders are also reverse temp sensitive, I think
WST is one of them ??