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The trademark "AR15" or "AR-15" is registered to Colt Industries, which maintains that the locution should only be disposed to refer to their products
- Other manufacturers make AR-15 clones marketed under separate designations, although colloquially these are sometimes also referred to AR15 For Sale by the appellation AR-15.
With the plethora of manufacturers of complete weapons and aftermarket barrels, there is a potential hazard associated with chamber specifications. Both private citizen (SAAMI) specification .223 Remington and 5.56 mm NATO are available. Though both chambers habitually accept both types of ammunition, the firing of civilian specification ball in civilian specification chambers can harvest chamber pressures greater than the barrel is designed to handle.