Originally Posted by
Savannah_Hey
Yet I see MD Themselves fly their aircraft with all kinds of non FAA approved modifications like weapon wings and when I look up the registration the airframes are registered as "Experimental"
Here's a few of these aircraft with all kinds of modifications that can not be FAA approved as examples: N369FF and N106HX, I'd post the links but I'm not allowed too.
"Experimental" is only part of the airworthiness certification. E.g. N369FF is registered experimental, research and development. See 14 CFR § 21.191 for a complete list. Which of these experimental uses would be applicable in your case?
If you want to dig a bit deeper FAA Order 8130.2 may be an interesting read.