I would be curious to see a measurement of base to shoulder dimension (head space) of the ammo that is failing to fire. I'll bet it's on the short side of SAAMI spec. and possibly your chamber is on the high side.

That would be a likely cause of FTF, especially with primers known to have a hard cup. Do you have gages to measure the headspace of the cartridge?https://www.midwayusa.com/product/10...ith-comparator

If you have one (or get one) and make this measurement, compare it to cases that have been fired from your chamber and let us know what the difference is.

At the range last week I spoke to a shooter who complained about a particular batch of brand name primer having a FTF rate of something like 40%. I suggested he check his primer seating process and cartridge headspace. In return I got a quizzical look from him that told me he was perhaps new to hand loading.

When the cartridge is formed with a minimum or short base to shoulder length (head space) or fired in a chamber with a too long head space setting (bolt face to chamber shoulder) the firing pin will hit the primer and slam the cartridge forward against the shoulder while significantly reducing the firing pin hit energy. In extreme cases this might be so far forward that the firing pin is no longer making contact with the primer. In many cases a FTF will occur but sometimes will fire if tried again.