300 blk has some niche applications:

a) really short barrels: this requires a pistol brace or building a SBR

b) the GWOT is over, and people are less focused on imitating operators.

c) the percentage of people that would actually invest in NFA items like suppressors is still very small, and without a suppressor, you can't shoot suppressed.

d) the current craze is on general purpose rifles, recce rifles, and special purpose rifles.

e) almost every state that allows straight wall cartridges for deer hunting, now allow 5.56; and ammo manufacturers are making 5.56 hunting rounds. .

f) there are other cartridges stealing the "not 5.56" AR15 hunting round market. (350 legend, 6 mm ARC, 450 bushmaster getting more popular, etc)

g) 5.56 is still cheaper, and inflation is eating up a lot of people's budget. Food prices are going through the roof, so do you want to pay 40 cpr for .223 or 60 cpr for 300 blk to shoot at the range?

h) pistol caliber carbines also exist, and eat into the subsonic market for 300 blk.

i) the influencers that got paid to push 300 blk, already have those videos and need to make new content.

j) The war in Ukraine is changing people's expectation of SHTf and future war. Out with night time raids on insurgents, and in with drones, counter drones, and more distant engagements.