6gt ARC CDG and light primer strikes

Did you pull the bullet on the non-fired rounds to see if there was powder in the case and if the primer actually fired? What was the sound when you had a non-firing cartridge?

Did you by chance measure the primer pocket depth before hand? Primer seating depth after seating?

I'm not trying to get you headed down any rabbit hole of measuring/sorting primer seating depth on the regular, but mainly as a troubleshooting tool here.

If the primer pocket is fairly tight - and my limited experience with Alpha OCD brass in .308 Win SRP says 'yes' - then you do need to pay some attention to a) what the primer pocket depth is, b) what the primer height (bottom of cup to top of anvil) is, and c) make sure that you're actually seating the primer far enough in to where the anvil has some pre-load/crush/consolidation (all terms for the same thing, depending on the literature/source) so that it will go off reliably. Otherwise it's entirely possible that all you're doing when you drop the trigger is just seating the primer a little deeper - but not actually crushing the pellet and causing it to go off.

I'm not saying that one can't reliably seat by feel, without checking the numbers... but if you're new enough that you didn't realize you had the wrong primer ram in place, you might not be there yet.

I'm guessing you're measuring the depth with the tail of your calipers? Not the best tool, but short of spending $$$ on a dedicated device, certainly usable.

Pocket depth (0.124) minus primer height (0.120) gives a difference of 4 thou. So for the primers to be just touching the bottom, they'd need to be 4 thou below flush. Ideally, for a bit of pre-load/crush, you want them 2-3 thou below *that*, so say 6-7 thou below flush (in this example).

Just food for thought...
7 of 10 is a pretty high share of failures. In some ways, that is bad but in a way it should make it easier to isolate the root cause.

If the ammo situation allows it, I would take about 10 to 20 of those factory rounds with me on the next test session. You may find an obvious cause but if something still isn't right, then I would go back the last ones that were still working and verify they still do.

The fishbone diagram for troubleshooting a bolt gun failure can be long, but you can cut it down by splitting the search between the gun and the ammo.

By chance, have you also checked the headspace/shoulder datum length of your virgin loads versus the factory?
How about the shoulder datum length after firing the ones that did ignite?
While primer seating depths can play a role, so does the way the cartridge sits in the chamber. If a case is short and a chamber is deep, we can get problems.

Did you go back to factory ammo and have no failures?
Did you inspect the bolt and firing pin spring?