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Posted: 4/6/2009 5:36:00 AM EDT
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I have a few questions..
Was out shooting this weekend and a buddy a box of 5.56 rounds. I did not shoot them because I believe I am chambered 223. I have a Shurluk upper with the keyhole marking. Is it 5.56 or 223? I took one of his 5.56 rounds home to measure aginst my 223 rounds...they look exatcly the same. I then found 7 different brand 223 rounds and lined them all up and got the calipers. they are all pretty damn close. 3 of the 7 rounds have a slightly slightly longer projectile but all measure 223 dia. set the calipers for 223 then switched from inches to mm and it shows 5.66! calipers broken? this tells me that the 223 bullet/projectile is larger diameter than a 5.56. this is wrong I thought.  wtf?
Anyone know of a link to a drawing of the two different rounds with their dimensions? .223in/5.56mm I understand that the shell is supposed to be different but since I have none to physically measure....???? is the projectile the same 223/5.56? Just the shell is different? Ok now here is the funny one for you guys if that wasnt enough. I noticed that a unfired round does not fit down the muzzel. I never tried this till the 5.56/223 came up. Tried it with other cal. guns and none of them fit down the muzzel. whats the deal with that? I figured it woud be a snug fit but not oversized. where does the extra metal go? does it get stripped from the projectile on the way out the barrel or does it reform to fit? Is this the main reason barrels get hot? |
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The general skinny is that
1.) 5.56 is loaded to higher chamber pressures 2.) 5.56 brass is thicker than commercial .223 brass 3.) Bullets (the part that comes out when the cartridge goes bang) are dimensionally the same #2 above is one of the prime reasons for #1, since the thicker brass reduces the space inside the case, therefore increasing the pressure. There can be other differences between mil-spec and commercial-market ammo, such as primers, powders, etc., but suffice to say the old rule is a good one to follow - .223 okay in 5.56 chambers, but no 5.56 in .223 chambers. Difficulty in chambering could result from the difference in barrel configuration between .223 and 5.56 chambers. . . |
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