Found a lonely box of this stuff for cheap at my local big-box. I've had good luck with Sellier & Bellot - I mean, who here doesn't appreciate Czech toys?

Tested head to head against Norma Tac-22 and CCI Clean, both discussed in earlier threads. Mark IV at 10, free fire, warm and sunny. I like.

It's a dry graphite-lubed subsonic LRN, best used for punching holes in paper, but it's very very good at that. The most consistent of the bunch by a narrow margin - Norma Tac-22 technically scored as well, but S&B Club shot a marginally tighter group. Without any of the disgusting grease. No failures, no flyers.

CCI Clean 22 is just as reliable and just as clean. Actually more accurate than either of the others in my gun, but not as precise. That is, it shot closer to the point of aim, but the group was an inch wider. Fine for plinking steel though.

Not quite as satisfying as the plonk from 230 grains at 800+, but that's a different thread.

So sub-sonic will cycle your MK IV? I would have thought not.

I’m going to try the S&B subsonic in my Mk IV suppressed, to see if the added back pressure from the suppressor helps cycle it.

I also green that CCI Clean is good stuff.

I have never had any problem with cycling subsonic ammunition in the Mark IV. The worst I've ever tried was CCI Copper at 21 grains and something stupidly fast. It turns out that momentum is more important than energy when it comes to cycling a spring-loaded bolt. Mass matters.

I've had very few problems at 40 grains. Cold temperatures play merry hell with wax lube on lead bullets, so I've abandoned them for polymer and plated. The only problem I've had with metal plated .22LR was with Winchester Silvertip after a long range session, when the chamber and barrel were dirty to begin with. The same ammunition works fine as long as the gun is clean, so I don't disparage it. It isn't target ammo anyway - it's meant as a defensive round, and as such it should only ever be shot out of a clean gun.