OB: Try some federal primers then. Even if that cures the problem(it should), I'd be a little leery of a trigger job that won't light off one of the major manufacturers products. That means factory Speer gold dots could be problematic in that gun. Not a good thing.
As for primers, they're like any other component in the hand loading realm. Different approaches by different makers. I use Federal primers by the thousand in progressive machines, and have had no trouble with them. The "warning" out there about using them in progressive machines is to save the terminally clueless, IMO. Run the press at a decent pace, keep it properly maintained, and don't force things. You'll be fine.
I use almost exclusively Federal primers, I've found them more consistent in dimension and more consistent over the chrono than other brands. YMMV of course.
Brass is the same way, different results from different makers. I love Federal pistol brass, but detest their rifle brass, same with Winchester, yet with Remington it's the exact opposite.