PCC power factor varibles

[jmcqueen]

My JP13 has a velocity a lot deviation as a result of being a blow back action. Sometimes 60-70 fps. Slow powders are worse in this regard than medium powders. What I find is that I need to use the lowest velocities out of the strings to decide on my power factor and the proper load. If I load using the average I can end up with some rounds under power factor needed to function the gun well. It only takes 1 in 100 cause a interruption.

[2scoops]

Agreed. Found the same with slower burning powders. Take note what brass you're using as well. If you have a mixture of brass it impacts the amount of deviation significantly. Same brass (brand, number of times fired) will reduce deviation