Like anything else, there can be problems.....or not.
Problems range from poor quality or simply defective extensions, to people who install them wrong, or who improperly convert one of the Remington Express guns to accept an extension.
As long as you buy a good quality extension, install it properly, and use a barrel clamp, there usually aren't any issues.
The extension has been being used on shotguns since the 1950's so the technology is well proven.
