Just cheked Midway-said expected in stock 2/22 B/O ok.
midway link
It's not primer only but I think it's like the CB's that I've used. quiet but not for semiatos. They are lead, I don't think the fouling would be bad if your not shooting thousands of 'em. Reg cleaning should do the trick.
"This quite round produces a report that is 1/4 the perceived noise level compared to standard velocity 22 Long Rifle Rounds making this round perfect for backyard plinking, youth shooting, or shooting in areas where noise may be a concern. This round is ideal for bolt-action and single shot rifles (but is perfectly safe in semi-automatics). "
I've got 'em backorder myself.
It's only a few weeks away, In the meantime,I'll have to keep an eye out at Wallyworld and other local fun stores for 'em myself.