Committee of Safety muskets were built to contracts from the Committees of Safety between 1775 and 1777, and are mostly copies of the Short Land Pattern Musket. Militia muskets are a different thing, being basically an American made-musket of any type. "Fowler" basically designates a smoothbore that doesn't fall into another category, can come in any caliber between .50 and 10 gauge, and could be anything from silvermounted to shimmel-type - there are plenty of recycled parts shown in Grinslades's book, and at least one without a buttplate. Furthermore, the line between militia muskets and fowlers can be kind of blurry at times - is a smoothbore built with the lines of a New England fowler, but cut back at the muzzle for a bayonet a fowler or a musket?
There was a fellow on the old board that was making a parts-built musket based after one in a Neumann article, but he seems to have dropped of the face of the earth a year or so back. I myself have "smoothbore" on the "to build eventually list", and have been thinking about a militia musket of that sort.