Receiver extension buffer system choice for suppressed 300Blk SBR

[MisterHelix]

...or, will having an adjustable GB make the choices moot? Will a standard carbine spring and carbine buffer be just as good?

Of the three 300blk's I have, none have an adjustable gas block. Two of them are Noveske 10.5"'ers (pistol gas/standard carbine extension and spring, and H2 buffers). The third is 16", and has carbine gas, and the VLTOR A5 extension and A5H0 buffer. (Built primarily for supersonic hunting loads).

All three will run supers or subs, suppressed or unsuppressed.

I think you're overthinking it.

(Though I don't think there's any drawback to the silent/captured spring setup, aside from non-standard parts, but that's also true for the VLTOR A5)

" The shorter than standard carbine action systems are less forgiving than the standard carbine action systems. Going to shorter action systems for this reduces the span of the operational envelope of function compared to the rifle like action system. You can make shorter ones function, but the application becomes more dedicated to more specific combinations."

Though I think the above statement is spot-on for 5.56 's, I'm under the impression that for 300blk, the pistol length gas system is the most "forgiving", particularly when considering subsonic loads. When seeking to use a 300blk in all four configurations (supersonic suppressed/supersonic unsuppressed/subsonic suppressed/subsonic unsuppressed), pistol gas is the default for functionality. The downside to this is that suppressed supersonics are typically slightly over gassed.