223 Remington vs. 5.56 NATO - What's the Difference? – Top Brass Reloading Supplies

Case cartridges for the 5.56 NATO (5.56 x 45 mm) and the .223 Remington are very similar. For all practical purposes, the external dimensions are identical, and one can effectively say that there exists no difference between the two. Both are designed to accommodate a .224 inch (5.56 mm) bullet between 40 to 85 grains

223 Remington vs. 5.56x45mm — Facts vs. Fiction « Daily Bulletin

223 vs. 5.56: Ammunition Comparison and Overview

223 vs 5.56: What's the Difference & Which to Choose? - 80 Percent Arms

A Guide to the 5.56 and .223 Cartridges - Wing Tactical

223 vs 556: What's the Difference?

223 vs 5.56: Comprehensive Caliber Comparison by

Best Coyote Cartridge: 223 vs 22-250 - Petersen's Hunting

Reloading 223 / 5.56 From A to Z – Ultimate Reloader

Commercial vs. Military Brass - What's the Difference? – Top Brass Reloading Supplies

223 -vs- 5.56: FACTS and MYTHS – Ultimate Reloader

223 -vs- 5.56: FACTS and MYTHS – Ultimate Reloader

What's the Difference Between 5.56 and .223? Are They Interchangeable? Does it Matter? - The Truth About Guns