WW296/H110 are great for Magnum loads at their hottest, and nothing less. The low end of even published data can produce extreme spreads of an increasing number the lower you go. Up near max and accuracy starts to suffer (not sure if thats me flinching from the big BOOM) but in the "sweet spot" 296 is a great one for FULL HOUSE loads.
Ive noticed this, and not sure its relevant or not. But the sweet spot in WW296 is pretty much where the bullet is seated right up to where the powder ends. NOT compressed, but NOT even a 1/16" gap between powder and bullet. (44 mag and 357mag)
If you use 296, OAL is very very very important in dictating pressure, more so than with some of the faster burning powders, IMHO. Use bullet, primer and Powder data to the "T" for best results. I personally only use Jacketed "heavy for caliber" bullets with cannelure, and use a nice roll crimp into the cannelure.
I believe that if 296 is downloaded to where there is airspace enough for the primer ignition to pass over the powder in the case, allowing for sporadic ignition, there can be a huge list of issues, including but not limited to....pressure spikes, squibs, poor accuracy, velocities all over the place, unburnt powder and dirty chambers and barrel. KB not out of the question.
Work with WW296 and get to know her. Those that do. fall in love with her!!!!