Thinking of some of the things I have encountered:
Bullet velocity appropriate? I had 221 FB with a subsonic load print 55s sideways at 25 yards
This is multiple rifles? To rule out badly eroded barrel
Jackets damaged on the bullets? Overcrimped?
Wetting your pants laughing from watching the smoke bum taking a big drag of hair smoke and then gagging or puking!🤣
Burning horse hair is NASTY smelling!