I hope one you you guys can answer this. I can't. One of the children that was at the range, ask me a real question today.
He picks up a round and puts it in the muzzle of the piece. He then asks, "How does this come out if it won't fit in here?? [:0]
This is me standing there looking

Thanks

The bullets used in a .223 are size .224". 0.223" is the distance between the groves of the rifling in the bore. The bullet is oversized to guarantee a sealed fit so that gas does not blow past the bullet and so the rifling will engage the bullet fully.

Jonathan

I thank you very much. I have learned something, and I will past this on to the child. Pretty smart on his part I was thinking.

Thanks again.
B

Well DsrtEgl is mostly right, although the numbers may be a little off... Usually there's more than .001" difference in the diameter land to land, and the bullet diameter, although the groove to groove distance is usually the same as the bullet.

At least in the US.  For instance, a .308 uses a .308" bullet, but the barrel diameter is .300" before the rifling is cut into it.  The distance groove to groove is then .308.  This makes the bullet seal in the barrel.  The rifling CUTS into the bullet when it goes through the barrel.  

This means, if you try to shove a bullet in from the muzzle, it will not go in without SIGNIFICANT force...  If it DOES go in easily, your rifling is likely worn/wearing out.

Well, I was speaking of the general case for groove diameter and leaving the height of the lands out of the discussion.

But yes, the lands cut into the bullet and the land to land diameter is significantly less than the groove diameter.

Most bullets are slightly oversized in relation to the groove diameter (to ensure a tight gas seal). In my findings, most jacketed bullets are over by 0.001" while non-jacketed bullets vary from 0.002" to 0.003" over nominal groove diameter.

Jonathan

A wise old man once told me,

You can train a dog but you must be smarter than the dog.

I think the kid has you beat in this dept.