Why would "they" make a AR with a 10.5" or 11.5" barrel and then put a 5.5" flash suppressor on it? Could'nt "they" make a flash suppressor work back then? To me common sense would tell me if the overall lenght is 16-17" why not have a 16-17" barrel. (back then is 1965-nam-1975)

That's a very good question.

^ [:)] ^

answer is simple becouse they could

i dont get the 11 inch barreled uppers with 5.5 inch Flash hidders. but hey whatever floats your boat i guess

the xm177 was intended as a "sub-machinegun" with a 10in bbl that ended right in front of the front sight. colt developed a f-hider with a built in sound "moderator" to tame the bark of the xm177 as the noise was unbearable. the barrel was later lengthened to 11.5 to enhance reliability. the long f-hider you see on the "car-15" has chambers cast into it, much like a suppressor- and for the same reason. this f-hider was eventually ruled a suppressor by atf. semi auto "car-15's" had the 11.5 in bbl with a lengethened f-hider welded on to preserve the "car" look while conforming to the 16in o.a.l. requirement. someone will be along to ammend and correct me shortly.[:D]

The original short 16's (XM177,et al)were an attempt to get the smallest possible package that would take standard mags/ammo to replace the huge variety of subguns that were being used. The short barrel was used in conjuction with a flash suppressor/sound moderator that was approx 4.5" long. Those original units are classed as a sound suppressor.

This thing with 10.5" barrel and 5.5" flash suppressor that we see now is just cosmetics, like pinned "collapsible" stocks.

Thats just the basics. I think it is covered in detail in some of better AR books

Thanks guys! acept 777 [:)]

The ones you see now have never made alot of sense to me, and after reading the effects of barrel length and velocities and bullet performance (ie fragmentation range) in the AR15.com Ammunition FAQ they make even less sense. ( 11.5in. barrel M193 rd. below 2700fps 40-45 meters. M855 round same barrel below 2700 fps in 12-15 meters).

fashion often overcomes utility.

i repair and sell household appliances- see it all the time.[rolleyes]