Colt 9mm SMG with EOTech Holographic sight in service with OCTOPUS cdo of Andhra Pradesh
Colt 9mm was developed around 1980s to supplement 9 x 19mm SMGs in various SWAT forces in the US,mostly H&K MP-5.
Colt Designers were overlooking compactness of 9mm parabellum in lieu of versatiliy of 5.56 x 45mm. Thus,when they finally realised even in era of automatic carbines,9 x 19mm still has a chance in law enforcement forces.they started developing a new 9mm SMG predominantly based on M16.
The main reason behind choosing M16 as base platform was mainly because of requirement - A large chunk of SWAT Commandos and other law enforcement staff in police forces there consisted of ex-military guys and combat veterans who had seen actual combat in many places
so having a gun that is ergonomically similar to their service rifle M16 would drastically cut training times on a new weapon.
Designers at colt, initially developed an Open Bolt Gun in M16 Shell with two safeties. One being conventional safety at fire selector,and other was Grip Safety,quite an Uzi type,to be honest.
This Open Bolt 9mm variant also took modified Uzi mags (since they were straight compared to curved magazines on MP-5,putting them on modified mag well won't be much difficult.Though early mags for MP-5 were straight as well,but ultimately they chose Uzi mags).
They faced some severe issues in very first variant of the gun such as Ejection on this one was quite violent and early variant SMG didn't have a case deflector. Recoil was comparatively violent,hence controllability issues and so.
That simple 'jugaad' of putting a Uzi mag on gun by a simple magazine insert 'adapter' thingy didn't perform so well and some jams occured.
They learned their lessons from this early prototype and realised a dedicated receiver and bolt carrier was needed for such gun.
In later variant,they prefered a closed bolt gun. Plus,they removed 9mm bolt and simplified Bolt Carrier to make it a complete blowback type design and instead of magazine insert,they designed a special lower receiver with its own unique trigger group (to rectify firing pin breaking issues) and removed that grip safety since it was creating stoppages.
This later version proved quite good SMG and these variant was adopted in many law enforcement agencies as well as military forces as 'Colt 9mm SMG'.
Some Plus of this gun :
+Accuracy was quite excellent
+Very Similar ergonomics to M16,so commonality in training
+Sights were also quite similar to M16
+Since this SMG was of simple blowback type closed bolt gun,reliability on this design was quite superior to other 9mm SMGs
but all things apart,greatest + of this gun was..
This SMG alone was able to fire many different types of 9mm Ammos without much issues. Operator can fire both normal,subsonic or low pressure cartridges and +P (High Pressurised) - all these major type of rounds in same gun.
Compared to MP-5 this 9MM SMG is quite superior gun,but still MP-5s are predominant in this caliber group because of their early inception and quite prolific numbers it is too hard to avoid the MP-5.
Colt still sells these 9mm SMGs,and current gen ones are modernised with P-Rails and other features. ^^Wish we had procured these 9MM SMGs instead of beretta MX4 storm with BSF ( though we tested it in trials and it supposedly failed ).