Before we make this far more complicated and costly than it truly needs to be...
Try this:
Empty or remove the reservior that holds fresh primers.
Get an old, thick, bath-sized towel. Fold it in half and completely cover the press so that you can work the handle but the entire blast zone is otherwise shielded.
Now, with just one primer, slowly but surely with increasing strength and pressure -- seat the primer. Don't stop until it either seats properly below flush or it EXPLODES in your attempt to seat it.
Can primers in .38 seat with more difficulty than .45?
ABSOLUTELY, for sure, no doubt.
If you change brass or primer brand, things can also change.
One thing that we can always count on is that newer handloaders always have a (very rational, expected, and helpful) -FEAR- of primers and priming.
Using a towel and safety glasses should help you to learn, hands-on, just how much force it would take to detonate one.
NOTE: this only works when your primer is lined up properly! If it's half way of centered or sideways, YEAH, you'll make it go bang. But if it is lined up as it should be, don't be afraid to be the boss.
Nice even movements, never a sharp stab.