Static! Wipe bottles with a dryer sheet, and even use a humidifier in the room in the winter. (At least in cold weather)
Side note; I've been using Red Dot for 35 years, and now have tried Clays. I've always had a small amount of residual gunk in the barrel after shooting Red Dot, but the Clays powder left my barrel clean of the residue. Shot one round with Red Dot and had gunk, shot the next round with Clays and it actually blew the gunk out. Both powders were new within a couple weeks, (maybe the Red Dot sat on the store shelf longer, but it's been that way for years). Not sure why it worked that way, but I'll be a Clays user from now on!
Side note; I've been using Red Dot for 35 years, and now have tried Clays. I've always had a small amount of residual gunk in the barrel after shooting Red Dot, but the Clays powder left my barrel clean of the residue. Shot one round with Red Dot and had gunk, shot the next round with Clays and it actually blew the gunk out. Both powders were new within a couple weeks, (maybe the Red Dot sat on the store shelf longer, but it's been that way for years). Not sure why it worked that way, but I'll be a Clays user from now on!