If the chamber adapter is machined to short then the whole 22 bolt/kit will be to short or if the barrel is machined to deep
were the collar/chamber adapter fits up against, then the whole 22 bolt/kit will be to short.
When you put your 22 bolt/kit in the upper it should be a flush fit not a sunk in fit.
it should look like this
.
notice the tab on the top of the 22 kit, that tab should be up against the lower receiver when closed and will
keep the 22 kit snug against the barrel so it wont move when you pull back the charge handle, only the
22 bolt will move not the rails or the chamber adapter.
The other problem is when the chamber adapter is bored out to big ID or the barrel is
lathed down to small OD, then you get a sloppy fit.
.
If the barrel or extension is machined to short between these two lines then this can cause the
22 kit to be loose.