This is what I've got.
Sean: bolt, carrier, mini op rod
TChris: 2 plugs Type 1 SPK
Flsk: Type 1 and Type 2 SPK, one 5.56, one 762 plug
TTE. I'm out of SPKs at this point. I've got some of the small parts but not enough to make a full kit. WRT your barrel 300 and working with a barrel in 5.56; RA said they offer other calibers in the blackout gas system length. It's possible to get that and not swap out the op rod/tube... BUT RA (and I agree with them) suggest going with the longest gas system the barrel will take. The short blackout system is going to create a lot of dwell time on the much higher pressure 5.56. 9.5" would fit and look similar to the 300 but the longer the barrel gets, the worse the pressure is going to be.