I use plenty of H110/W296. I always use a Mag Primer, and I always give the bullets a stout crimp when using that powder.
I just loaded some 357 Mag with W296, I really wanted to use those Arg SPP that many of us recently bought on the NormaUSA deal, but I dug deep into my stash and found some CCI Mag primers and used those instead, I am getting low on them.
Yes! I cut my 200 meter revolver groups in half switching from a standard primer to the CCI 550 mag primer. Did the standard primer work? Yes but not nearly the burn consistency or accuracy with H-110 as the mag primer.
I’ve used 296/H110 in the .218 Bee,.30 Carbine, .300 BO, magnum revolvers and .410 shotgun- but never in .223 - but I don’t load cast bullets in my .223 rifles.
I can't tell the difference in BO loads with H110/296, 2400 or Lilgun - mag vs normal CCI primers. Hodgdon does testing with srmp for a lot of loads, maybe it gives reliability to their data. 110 in 223 sounds risky to me.