1 Monocot and dicot are short for monocotyledon and dicotyledon. 2  Mono-means one, and monocots have one cotyledon. 3  Di-means two, and dicots have two cotyledons. monocot plant has one cotyledon (scutellum) in its embryo whereas a dicot plant has two cotyledones. 2. A moncot pl â¦ ant has generally isobilateral leaf with parallel venation whereas a diicot plant has dorsiventral leaf with reticulate venation. 3.
The AR-15 was developed as a lighter, 5.56 mm version of the AR-10. The AR in all ArmaLite pattern firearms simply stands for ArmaLite, and can be found on most of the company's firearms: AR-5, a .22 caliber rifle; the AR-7, another .22 caliber; the AR-17 shotgun; the AR-10 rifle; and the AR-24 pistol.
The U.S. Air Force and the U.S. Army adopted AR-15 variants (as the M16), and modified the .223 Remington cartridge slightly (by switching the powder to one that would produce a higher velocity), this cartridge becoming the 5.56x45mm NATO.ifle receiver extensions are used with fixed-stock AR-15 rifles, and are slightly longer than the carbine-length receiver extensions. The corresponding action spring is generally between 11.75 and 13.5 inches long; any shorter, and it should be replaced.