Quoted:
The CMMG .22 conversion is designed to be a simple plug and play unit. All kits are tuned from the factory and do not require any modification.
Whatever happen to SIMPLE PLUG AND PLAY.
If the kits have been disassembled as has been suggested,
that is the fastest way to do away with simple plug and play. They are tuned, they are tested before shipping. Keep in mind not all uppers and barrels are made the same either. Distorted frames can cause all kinds of issues.
The only time we recommend full disassemble, is if there is parts breakage. It doesn't sound like this is the case.
On one vid it closes all but 1/16". Some kits will drop straight in like you are trying to do while others won't. This does not make it defective. Once the kit goes as far as it will go, give the kit a slight twist in one direction or the other and push. This is normal with some kits.