Can you provide examples of his problems with the rules of evidence? Why would he even be involved in anything to do with admissibility? As you said, he isn't a lawyer.
No, he doesn't have a reference, but he at least has a reason for his position, and I don't recall him going house to house making sure that good, law-abiding armed citizens don't use handloads. But for those who've asked his opinions on the subject, he can give a well-thought out answer.He is an advocate against using handloads, while Speer and Hodgdon support handloads for defense. And after repeatedly asking, Mas' still has yet to produce any case number or reference other than his own writing... kinda makes you think, doesn't it?
Yeah, it does make me think---makes me think he gives a lot of thought to lethal force issues, and makes me think that he is, therefore, somebody whose advice I would want to seriously consider.
Edited to add: Oh, now that I think of it, while Mas is not a lawyer, he does have prosecutorial experience. His jurisdiction in NH allowed officers (I forget what extra certification was required) to serve as prosecutors in court, and he did so. I would expect, therefore, that he does have a passing familiarity with the rules of evidence.