New technique which is worth mentioning for those taking on the task themselves.
When you heat the receiver to break down the threadlocker, you’ll want to let the receiver cool down before you attempt to install the new extension with Loctite. If the receiver is hot, the Loctite will cure much too quickly which can impede your work in installing the extension.
I put the receiver in the deep freezer for 5-10 minutes after heating them to get around this issue quickly.