Brief overview of iconic carbines. Part 2

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M16/M4/ Ar15 (9mm). Example Czech V-AR.

Early 1980s saw Colt (now CZ owned) step into the 9mm game, initially with a castrated (no gas system) m 16 / m4 Frankengun, first models used an Uzi like grip safety, fired from an open bolt and Uzi mag. They soon changed to a closed direct blowback bolt system. It’s been a process of little refinement since - the last ten years has however seen a big push from the civilian AR 15 gamer USPSA / IPSC market, match 16” barrels, match triggers, hydraulic and magnetic buffers but only over the last few years have different operating systems than direct blowback been coming along - CMMG radial bolt, Sig MPX gas system and JP and Stribog roller systems in an attempt to reduce perceived recoil. 

Sig MPX PCC. 40 round mag dump. Very controllable recoil.

https://drive.google.com/file/d/16ZEHeMGVR1h9ZnANTHO1-qmUhkkHv_g-/view?usp=drivesdk

Direct blowback in 9mm gives more recoil than a 223 direct gas impingement system - it didn’t bother Colt, they wanted to push M4s, no real military interest in 9mm and LE were happy with a 50 year old HK mp5 system. The civilian PCC gamer market has pushed development of the ar15 system.

AR 15 9mm weighted bolt required in a direct blowback system.

 

New millenniums, ( Stribog, B&T, Scorpion Evo).

So LE had been using the mp5 for the best part of 50 years. It made no sense to military with a better .233 cartridge in every respect but LE a 9mm carbine with compatible pistol 9mm ammunition and suppressors for covert use made some sense. But not the 16” PCC gamer guns that were bigger than 223 rifles. Enter the likes of Stribog and B&T and CZ.

Stribog Gen A1

what you get ( Stribog) is a cnc machined monolithic upper that is picatinny and/ or m-lock compliant for easy mounting of optics, lasers, lights and the kitchen sink. Space is at a premium. The Stribog AI uses a blowback system but bolt mass is placed over the barrel therefore not much center of gravity shift during cycling so still flat shooting. The A3 version uses a simplified roller delayed system that saves about 6oz in weight and reduced preceived recoil by around 15%. 

There is a trend for lowers to  become polymer with chassis like fire control groups - so you change out a lower shell to suit your magazine choice be it proprietary but Glock and now Sig 320 mags are the dogs danglies as most LE use Glock pistols and the US army has adopted the Sig m17 (320) pistol. There is also a fair bit of tech crossover from the PCC market - B&T uses a hydraulic buffer like those developed for AR15 gamer guns. State of the art in a LE type kit is something like this B&T APC 9 PRO G SD  - still direct blowback but with hydraulic buffer, Glock mag compatible lower and integral suppressor.