Historical What-If: The CAR-15 SD

What is the MP5 was never adopted, and instead the vented barrel and telescoping silencer used by the SD model was instead developed for the AR-15? Broad River Tactical thought it would be fun to follow this line of thought, and builds an MP5SD style barrel and handguard system for the AR – and I think it’s a very fun and very cool concept.

This example uses the CMMG rotary-delayed blowback action, and EndoMag 9mm magazines in regular 5.56mm Pmag bodies. That means the whole system works with a standard AR lower, instead of needing a dedicated pistol-magazine lower. The silencer is a clone of the H&K SD type made by HiTec Arms, and it is a fantastically quiet combination!

Disclosure: Broad River Tactical send me the upper for free, and I put it on an SBR lower I already had. I bought the silencer. I have no other relationship with BRT or HiTec Arms.


  1. I don’t know that the German engineers would have made much headway in the American gun industry post-WWII.

    You’d like to think that they would, but… The insular nature and closed-shop mentality of the guys at Springfield would have likely prevented anything like that happening. Or, so I surmise. Hell, they had problems taking Eugene Stoner seriously, and he was an American. The military small arms industrial complex was nothing like the aerospace industry, in terms of openness to new ideas and people.

    On the other hand, who knows? It might have worked out, but… I could see a hell of a lot of frustration for any German engineers showing up to try and participate.

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