wildcat, port pressure, dwell time

[Chriznak]

Trying to brainstorm some kind of wildcat the compete with 4.6x30, 5.7x28, 6.8spc, 300black, etc. in the "PDW/SBR" niche of cartridges. Would like to run 150 grain 284 bullets out of a 5.56 case trimmed down & cold-formed to have COAL to function in STANAG magazines & AR.

I'm hypothesizing: a 10.5" barrel, carbine length gas port (like the MK18) but a slower bullet velocity (1800ish) ,dwell time may be sufficient for a smaller-than-MK18 gas port diameter ?

Great bonuses if possible:

if pressure at the muzzle got down to 9mm +p muzzle pressures so pistol suppressor could be used

if the bullet diameter is sufficient to prevent cartridge from chambering in .223-rifle since .284 is bigger than .223 case neck diameter?

if the if 223-shoulder is forward/wide enough to not end up being chambered in .284 wildcat chamber

if standard carbine buffer could be used

if barrel twist could be for 150 grain .284 SMK's to yaw/tumble on impact and shorter bullets like 150 grain fmj's to not-yaw on armor or 150 grain soft-points to not-yaw on game animals.

probably call it 7x38 for now

comment & make inquiries all you like, I'm bored this evening.