I'm not sure what barrel it is but the diameter is .575, same as my lightweight. It is about 20" and came from an AR with the old triangular handguard. It has the bayonet lug. It is marked 'c mp c'. I considered buying a flat top receiver and using the 1-12 twist barrel since I usually shoot 50-55 grain bullets. I bought some tools years ago and they are around here somewhere.
Rather than changing the Colt and possibly decreasing the value, I might be money ahead to sell it and buy a complete rifle with the features I want. A friend recommended the Rock River Coyote Carbine and a neighbor has the Rem R-15.
