Let's try to clear the muddy water a bit here. I have had nine years of experience with the Appleseed program, involving many dozens of shoots. That said, I am not in a "high leadership" position with the program. I am, however, confident of the good faith of those in those positions.
About "assumptions:" We all know the old joke about what making assumptions does. I don't entirely agree. I think assumptions do that to us when we confuse our assumptions with known facts. As long as we keep explicitly, firmly in mind that we are dealing with assumptions that are subject to change, those assumptions (or working hypotheses) can be useful and do not hurt us.
Please let me explain some things about Appleseed shoots. They are not "matches." They are better described as "marksmanship clinics." No rankings (or even scores) are published nor winners announced. The only prizes awarded are embroidered "Rifleman" patches, worth maybe a couple of bucks, for those who score at least 210/250 on the 25 meter course or 200/250 for the full-distance (100 to 400 yard) course of fire.
The mood is surprisingly non-competitive. Do some trick out their rifles? Of course. A few elaborately, but most in minor ways. A few come with brand-new rifles still in the factory box and plastic bag! Do some want to outscore their buddy? Undoubtedly. But in my experience, the great majority of participants just want to learn how to shoot better. Most have not installed competition triggers or otherwise tricked-out their rifles, beyond installing aftermarket sights or scopes, and sling swivels. Most have not even attempted to "clean up" triggers with professional or kitchen-table home gunsmithing. Most wouldn't even know how to attempt that, and have better sense than to try. No rigorous statistical analysis, just my firm belief based on my experience.
Regarding failure to sequester malfunctioning rifles, or document the condition of those rifles, or keeping statistics of all models of rifles used and identified as having problems: No, to the best of my knowledge, that hasn't been done. I don't see how that would have been practical to do. In any case, Appleseed isn't preparing for a product-liability lawsuit, so that isn't necessary. There is no intention of any legal action. This ban on M&P 15/22's is a temporary one, possibly erring on the side of caution, because of anecdotal evidence and a "gut feel" that problems with that rifle seem to be more common than with other models. And we did have a shooter experience a minor injury at a shoot.
The situation is similar for analysis of ammo brands used. No statistics have been kept. MY OWN OPINION is that it is impractical for Appleseed to keep a list of every manufacturer's ammo recommendations and attempt to enforce shooter compliance. If some brands shoot more accurately, or function better, or run cleaner than others, that's only to be expected. But any ammo that meets SAAMI standards should be safe to use in any appropriately-chambered rifle.
Is this proof of a significant defect in the 15/22? No. Hardly. That's why it's an INVESTIGATION, and interim corrective action put in place until it can be determined whether there even is a problem, or, if there is, fix it.
What is not an assumption is that I have an M&P 15/22, an older model, that is absolutely stock, and has had functioning problems. If it turns out to be appropriate, it will be sent to the manufacturer to be used as an exemplar to assist in the investigation. Nobody knows right now what that investigation will reveal. Have I done something wrong, to cause the problem? I don't think so, but it could to be. Remember, that's why it's called an investigation.
I'm not looking for a victory in court or a cash award or anything else. I just want my fun little rifle back, so I can use it with confidence!
Thanks in advance for everybody's patience and understanding.