M9 bayonet

M9 bayonet

M9 bayonet

M9 bayonet

M9 bayonet

M9 bayonet

M9 bayonet

M9 bayonet

M9 bayonet

M9 bayonet

M9 bayonet

M9 bayonet

M9 bayonet

M9 bayonet

M9 bayonet

M9 bayonet

M9 bayonet

M9 bayonet

M9 bayonet

The M9 Bayonet is a multi-purpose knife and bayonet officially adopted in 1984 by the United States. It has a 7-inch (18 cm) blade and is issued with a sheath designed to double as a wire cutter. It was designed and developed by Charles A. "Mickey" Finn at his R&D company, Qual-A-Tec. He later produced it under the Phrobis III name, filling a military contract for 325,000 units. Buck Knives was contracted to make 300,000 units and sold a commercial version under their own name. Finn's designs proved extremely popular, and were widely counterfeited and sold illegally by other makers. In 1986, Finn received U.S. Patent 4,622,707, however they continued to flow unchecked into the United States from Asia and Mexico, cutting into legitimate sales.
After the Phrobis III bayonet contract was completed, rights to the M9 reverted to the United States Army and there were many subsequent versions from other companies. It is issued by the armed forces of the U.S. and other countries, and has also been sold commercially in various versions.
Some production runs of the M9 have a fuller and some do not, depending upon which contractor manufactured that batch and what the military specs were at the time. The M9 Bayonet partially replaced the older M7 Bayonet, introduced in 1964. Although it has been claimed that the M9 may be more prone to breakage than the older M7; in actuality the M9 bayonet has a 20% thicker blade and tang (0.235" vs. 0.195") and a 75% greater cross-sectional area of steel in the blade than the M7.
The M11 bayonet, or M11 EOD is a version of the M9 specialized for explosive ordnance disposal (EOD). It has some extra features, such as a hammer pommel, but uses the same blade and sheath as the M9.
There have been four main makes of M9's: Phrobis, Buck (subcontracted from Phrobis during the original Army contract), LanCay, and Ontario. Starting in 1987, Phrobis subcontracted Buck, finishing up in 1989. It was around this time that Buck sold commercial M9s as well, which it did up to 1997.

LanCay got its first contract in March 1992 (taking over production from Buck) for 30 (later 50) thousand knives (with General Cutlery as a subcontractor); in 1994, there was another contract issued for about 100,000 improved M9 models. In 1999, a contract for 25,000 knives was split between LanCay and Ontario (12,500 each). Ontario Knife Company also participated in later contracts, and is one of the current (as of 2005) contractors for producing them. These can be identified by the blades, which are marked "M-9 / ONTARIO / KNIFE CO / USA".