I know of at least 1 person outside the RCMP firearms lab that actually knows the manner of conversion as you phrased it.
I've heard 3 or 4 different methods described by non-firearms lab people. Frankly, I do not believe that any of those methods are true. The RCMP has been careful to avoid releasing the information. In the A2A requests they blacked out all the information on 'national security' grounds.
Frankly, NO ONE KNOWS outside the RCMP.
Hasselwander does not limit the amount of time needed to "study the problem" only the time needed to accomplish the conversion. Just because the lab had the gun in their possession for 21 days (the figure you state) does NOT in fact mean they started working with it on day one... it may have sat there for a week or more before they ever looked at it.
This is partly true. The SCC did not consider whether or not the RCMP firearms lab would attempt to reverse engineer a failure of the test. As for the actual time spent in examining, it does not change the fact that the employees of the firearms lab are EXPERTS. Just because an expert can do something, doesn't mean a lay person could have figured it out. If it takes an expert, its not relatively easy.
Look behind the words to the intent of the judges. They aren't concerned with experts being able to engineer a full automatic firearm, they're concerned with criminals and lay people. When they say 'relatively easy' they mean relatively easy for a normal person.
From what I have been told about this specific case there is very little doubt (in my mind) that the court will have to confirm the RCMP's findings.
No offence, but I don't think you are particularly well informed on this. The RCMP has never released how they did it. Not even in disclosure upon a legal challenge by CanAm. They are still stonewalling the release of the information, even with undertakings to keep the reports confidential. In short, they're hiding the information, its reasonable to ask why.
The whole mess is a violation of the procedural fairness duties owed by the registrar. They have a duty to provide written reasons. Upon challenge they have a duty to disclose relevant documents. This alone is grounds to force a re-hearing of the issues. Then we have a question of whether or not the decision is due deference or not. My position is that it is not.