loss of fps/accuracy with same load ?

[MoaFlat]

I've Not yet had the powder lot to lot have significant change to my Audette Ladder best Node selection. Suppose there's a first time for everything. My first immediate suspect would be significant barrel fouling as the likely cause - either heavily carbon fouled, R33 is quite carbon dirty and some barrels with hot loads will require a good clean to restore accuracy. Some as much only after 25-30 shots and make sure you use a good gel cleaner that will get rid of most of it. Second call, could be excessive copper fouling - some projectiles, barrels and loads will copper foul more than others. Example, the hotter the Load the more carbon or copper fouling will occur. This Might require a foam in barrel clean if heavy fouling is discovered. And few badly fouled barrels might take repeats of this to eventually remove most of it. If left scratching your chin, take to your Smith or buddy who has a bore scope and make sure. Often I found after a serious clean - original ladder accuracy was restored- first round.