I have some PNW 300 BO loaded with 125 SST. Supposedly it's factory new ammunition.
It's not the best ammo, but it's functioned with no issues until last night. I blew two primers and the primers got stuck inside the M4 feed ramps. After clearing the jam and chamber, I thought it was a fluke and fired one more round. That round blew a primer too, so I stopped shooting. My question is what would be the primary reasons
for a blown primer?

Setup is a 8.5" SBR running a suppressor, and as I've stated no previous issues with gun or ammo.

I have read in reviews that blown primers were one of the chief complaints with PNW ammunition.

Blown primers generally mean a hot load. But, you are running it in an 8.5" barrel, which probably has a pistol length gas system. This gas port is much closer to the chamber end, which will increase pressures blowing back into the action. Adding a suppressor, this will also increase your pressures. So, shooting an 8.5" barrel with a short gas system suppressed, will certainly raise your pressure. If you have an adjustable gas port, close it up some to reduce the gas flow back into the action. If you don't have an adjustable gas block, then take off the suppressor and see if that helps. Without knowing what powder they used, it should be fairly hard to get a blk out load to blow primers. It's a smaller round that acts like a straight wall case. I've hot-rodded some of my personal ammo, and it will take a lot of pressure before it blows primers.

Take a look at these!! This is what I shoot!

Can’t help you with your blowout issue, but can vouch for Chad’s 125 grain ammo. My 16” Blackout loves the stuff.