Thats an interesting question! I hadn't thought of that, the Mutant Massacre hardcover is 320 pages and covers Uncanny X-Men #210-213, X-Factor #9-11, New Mutants #46, Thor #373-374, Power Pack #27, and Daredevil #238 so only 12 issues. If you added the other gaps between MM and FotM for UXmen, NW and Xfactor that would be

Xmen #210 - 219
New Mutants #46 - 54
X Factor #9 - 17

Plus Thor #373-374, Powerpack #24 and Daredevil #238

Which would be 37 issues. Add in FF vs Xmen 31-4 (I think that follow mutant massacre) to bring it up to 41 issues. Are there any other annuals or specials?

That would get Mutant massacre back into print in hardcover which was last printed in I think 2010 and fill in that gap making a nice omnibus between the assumed Uncanny vol 4 and FotM. What does everyone think?