The List
There are 307 4 letter words with M as the first letter. The highest scoring is MUZZ at 24 points in Scrabble. 2 of them contain no vowel at all: MYCS, MYTH.
MAARMAASMABEMACEMACHMACKMACSMADEMADSMAESMAGEMAGGMAGIMAGSMAHAMAIDMAIKMAILMAIMMAINMAIRMAKEMAKIMAKOMAKSMALAMALEMALIMALLMALMMALSMALTMAMAMAMSMANAMANDMANEMANGMANIMANOMANSMANYMAPSMARAMARCMARDMAREMARGMARKMARLMARMMARSMARTMARYMASAMASEMASHMASKMASSMASTMASUMATEMATHMATSMATTMATYMAUDMAULMAUNMAUTMAWKMAWNMAWRMAWSMAXIMAYAMAYOMAYSMAZEMAZYMEADMEALMEANMEATMECKMEDSMEEDMEEKMEERMEESMEETMEFFMEGAMEGSMEINMELAMELDMELLMELSMELTMEMEMEMOMEMSMENDMENEMENGMENOMENTMENUMEOUMEOWMERCMEREMERIMERKMERLMESAMESEMESHMESSMETAMETEMETHMETSMEUSMEVEMEWLMEWSMEZEMEZZMHOSMIBSMICAMICEMICHMICKMICOMICSMIDIMIDSMIENMIFFMIGGMIGSMIHAMIHIMIKEMILDMILEMILKMILLMILOMILSMILTMIMEMINAMINDMINEMINGMINIMINKMINOMINTMINXMINYMIPSMIREMIRIMIRKMIROMIRSMIRVMIRYMISEMISOMISSMISTMITEMITTMITYMIXTMIXYMIZZMNASMOAIMOANMOASMOATMOBEMOBSMOBYMOCHMOCKMOCSMODEMODIMODSMOERMOESMOGSMOHRMOILMOITMOJOMOKEMOKIMOKOMOLAMOLDMOLEMOLLMOLSMOLTMOLYMOMEMOMIMOMSMONAMONGMONKMONOMONSMONYMOODMOOIMOOKMOOLMOONMOOPMOORMOOSMOOTMOPEMOPSMOPYMORAMOREMORNMORSMORTMOSEMOSHMOSKMOSSMOSTMOTEMOTHMOTIMOTSMOTTMOTUMOUEMOUPMOUSMOVEMOWAMOWNMOWSMOXAMOYAMOYLMOYSMOZEMOZOMOZZMUCHMUCKMUDSMUGGMUGSMUIDMUILMUIRMULEMULLMUMMMUMPMUMSMUMUMUNGMUNIMUNSMUNTMUONMURAMUREMURKMURLMURRMUSEMUSHMUSKMUSOMUSSMUSTMUTEMUTIMUTSMUTTMUZZMWAHMYALMYCSMYNAMYTHMYXOMZEE