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Posted: 6/5/2006 11:25:44 AM EDT
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I was searching the site, and i couldn't find anything, i had the question... I was looking at a DPMS Precision upper, and it says it has a .223 chamber. Now, my understanding is that you can use 5.56 and .223 in a 5.56 chamber, but in a .223 chamber, only .223? It isn't a .223 Wylde, just says .223. I was looking at Radway Green, and if what i am saying is correct, i cannot use that in this particular chamber, correct, since i thought it was 5.56? Am i correct? |
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The primary difference between the chamber dimensions is the angle and depth of the leade (i.e., the throat). A ".223" chamber has the shortest leade, which increases accuracy with most factory loads, but also increases chamber pressure, as the bullet has less "freebore" before engaging the rifleing. The Wylde chamber has a medium-depth leade, and a "military" or "5.56" chamber has a long leade. Some long-range rifles have custom leades that are even longer, designed for shooting 80gr and 90gr bullets for 1000 yard competition. These ultra-long bullets can't be seated far enough into the case for the ammo to fit in the magazine, so they must be single loaded. In other words, they are only practical for competition use. Military ammo (i.e., "5.56" ammo) is loaded to higher pressures than .223 ammo, and if you put 5.56 ammo into a tight .223 chamber, you're going to exceed the pressure the system was designed for, and even though ARs are strong enough that it's rarely *dangerous*, it is often problematic, with common problems being difficult extraction, case head separations, popped primers, and other pressure-related issues. -Troy |
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I have a chamber reamer comparison that shows the differences between the various versions of 223/5.56 reamers. www.ar15barrels.com/data/223-556.pdf This will show you a basic drawing to explain the terminoloy. It also has the actual dimensions so you can see the exact differences. Maybe when Troy gets the ammo oracle site back up and running, he can add this to it... 
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