I interpreted that as meaning they had removed the research of the Rifle Mk.2, as you get the Rifle Mk.2 by researching the Rifle Mk.1.
My reasoning is that, apart from the above, after I built a Rifle Mk.2, I saw I could research it in the M.A.M., so I put it in there and built another one for my use.
When the M.A.M. had finished analysing, it didn't give me anything in return just "thanks, I'm done".
I put that down to "Experimental" and carried on using my other Mk.2 rifle...