Last I talked to Krieger they were unwilling to make anything smaller then a .22 cal AR-15 Barrel..when they drill the gas port they time the barrel so the gas port is in the barrel groove..I was told it takes to much time for them to make smaller caliber barrels because of this restriction....I did see at one time they were making 20 cal ar-15 barrels and then stopped..did they start again?.. thank you