As it was explained to me by a gun smith a couple years ago:
What will happen is you will get some buildup in the gas tube which restricts the flow of gas into the gas tube.
Over time with extreme build up caused by .22LR could be an issue that... Potentially, if you went to fire some .223 that there could be such a restriction in the gas flow (from .22LR build up) that the bolt may not be able to go far enough back to strip another round off your mag. In that case, a serious cleaning of the gas tube and or replacement of the gas tube may be necessary.
I have also heard that extreme build up in the gas tube can case the gas tube to completely fail when firing a 5.56 round.
Personally, I've never seen or heard of either happening. Though, I've always run 1-2 clean burning 5.56 rounds through after a day of shooting .22LR. (Notice I use 5.56 and not .223 just because of the slightly higher pressure which will blow out/burn off the build up from .22LR... Yes, .223 would probably work just fine but thats how I like to do it.)
While I've never had a problem, 5.56 is cheap If I'm just shooting 1-2 rounds as perhaps insurance to protect my $15 gas tube after shooting upwards of 500 rounds of .22...
To directly answer your question though: If you go out and shoot a brick of .22LR and wait a week then go back and repeat with .22LR it should not cause any malfunctions. The reason being, your worrying about the gas tube which is not used by .22LR conversions. The gas tube is, however, needed for the correct operation of the gun using 5.56/.223 and should be kept clear of blockages.
However... I've noticed that many kits need to be kept well cleaned... Should be fine if you wipe down the conversion bolt.
