.223 Remington / 5.56 chambers

[Jeff A]

I'm ordering a new barrel for a bolt rifle. I was planning on using primarily 68-70 grain bullets. The barrel maker says that I should get a 5.56 NATO Match chamber, not a .223. They say I can use my .223 Go and No Go gauges (this is for a Savage that I will be switching barrels on) and of course my .223 brass. I would like the option of using 52 and 55 grain bullets as well. I am unsure why I need to order the NATO chamber. Your thoughts?

 

[bigedp51]

I have a factory Savage .223 and the throat is longer than my AR15 rifles. Saami cartridge and chamber drawing are "recommendations" and not written in stone.

HOLLIGER ON .223/5.56 CHAMBERS
http://www.radomski.us/njhp/cart_tech.htm

Now look at the chamber diameter for the 5.56, it is .002 larger than SAAMI specifications for the .223 and the headspace settings would be longer. My two AR15 rifles have the headspace set at approximately the NO-GO setting for the .223. Meaning if the rifle was a .223 it would fail headspace testing, so WHY chamber a .223 to military specs and put up with a fatter and longer chamber.

 

[Turbulent Turtle]

Hold the phone here a minute. If the barrel maker is Krieger then you do want to use their 5.56 NATO Match chamber. They are the only ones that use the terms "NATO Match," that I know of, in describing their chambers.

I have one of those in my AR-15-based F-TR rifle and the only thing NATO about it is the size of the leade or freebore. The chamber itself is VERY tight and I have taken to using a small base F/L bushing die to resize the brass. I use the very long 80gr JLK bullet in my load and they are seated past 2.5 inches long last time I looked.

It makes for one very accurate rifle.

 

[Jeff A]

Hold the phone here a minute. If the barrel maker is Krieger then you do want to use their 5.56 NATO Match chamber. They are the only ones that use the terms "NATO Match," that I know of, in describing their chambers.

I have one of those in my AR-15-based F-TR rifle and the only thing NATO about it is the size of the leade or freebore. The chamber itself is VERY tight and I have taken to using a small base F/L bushing die to resize the brass. I use the very long 80gr JLK bullet in my load and they are seated past 2.5 inches long last time I looked.

It makes for one very accurate rifle.

The barrel maker was not Krieger. I was spooked and cancelled the order and went with a Shilen .223 with a .252 neck. Thanks for the input.

 

[Turbulent Turtle]

Who was it, so we can all be educated? Shilen does good work.

 

[stool]

biged is wrong.... dia of the case/chamber has no effect on HEADSPACE.

HEADSPACE is a number at a dia on the SHOULDER TO THE BOLT FACE,,,,,

nothing new

 

[Jeff A]

Who was it, so we can all be educated? Shilen does good work.

It was Benchmark. I did not know enough about it so just went with what I did know.

 

[Dvldawg]

You don't need the NATO reamer. Use the standard 223 chamber reamer and have it throated for the bullets that you intend on shooting..

 

[CatShooter]

"... the terms "NATO Match,"

The term "Nato Match" is an oxymoron... kinda like "Sloppy Tight".

biged is wrong.... dia of the case/chamber has no effect on HEADSPACE.

HEADSPACE is a number at a dia on the SHOULDER TO THE BOLT FACE,,,,,

nothing new

Big Ed is RIGHT - (Oh God, did I really say that? Big Ed is such a pest )

If the base to shoulder measurement is the same, and the shoulder angle is the same, then (ergo) as you increase the diameter of the body, the headspace datum line moves forward, and the headspace measurement gets longer...

... it's 10th grade math.

 

[MrMajestic]

Big Ed is RIGHT

What the heck did you have to go and say that for! We have to put up with him now!
Elementary= Don't poke the Tiger! ;D

 

[CatShooter]

Big Ed is RIGHT

What the heck did you have to go and say that for! We have to put up with him now!
Elementary= Don't poke the Tiger! ;D

(Shush... he paid me 50 cents to say that )

 

[Turbulent Turtle]

Big Ed is RIGHT

What the heck did you have to go and say that for! We have to put up with him now!
Elementary= Don't poke the Tiger! ;D

(Shush... he paid me 50 cents to say that )

It's not so much that people can be bought, but I am amazed at how cheap some people are to buy.

 

[bigedp51]

biged is wrong.... dia of the case/chamber has no effect on HEADSPACE.

HEADSPACE is a number at a dia on the SHOULDER TO THE BOLT FACE,,,,,

nothing new

I had no idea that so many people had reading impairments, stool try not moving your lips when you read. :

Now look at the chamber diameter for the 5.56, it is .002 larger than SAAMI specifications for the .223 and the headspace settings would be longer.

 

[Eddie Harren]

"Never correct a fool. He will only get angry. Correct a wise man. He will thank you."

 

[Turbulent Turtle]

I'm probably stepping into something I won't like here, but my thirst for knowledge must be quenched.

So here goes. My understanding is the datum diameter for the .223/5.56 cartridge is .330 inch. This is the point on the 23 degree shoulder at which the headspace measurement is taken; from that datum point on the shoulder to be bottom of the case. I fail to see how a larger diameter in the body would have any effect on the headspace measurement since the body diameter is always larger than the datum diameter. I would think that even if the diameter of the body was double of what it is now. the distance from the datum to the bottom of the case would remain the same.

What am I missing here? Please help me understand? I'm old and slow and there are so many negatives and undercurrents in the thread, it's difficult to keep up.

 

[CatShooter]

I'm probably stepping into something I won't like here, but my thirst for knowledge must be quenched.

So here goes. My understanding is the datum diameter for the .223/5.56 cartridge is .330 inch. This is the point on the 23 degree shoulder at which the headspace measurement is taken; from that datum point on the shoulder to be bottom of the case. I fail to see how a larger diameter in the body would have any effect on the headspace measurement since the body diameter is always larger than the datum diameter. I would think that even if the diameter of the body was double of what it is now. the distance from the datum to the bottom of the case would remain the same.

What am I missing here? Please help me understand? I'm old and slow and there are so many negatives and undercurrents in the thread, it's difficult to keep up.

Take a 223 case and stand it up. Now mentally envision the circle around the shoulder that is .330 in diameter, with a body diameter of 0.376".

Now expand the body diameter to 0.750, with the same shoulder/body junction measurement 1.438", and what happens to the cone that sits on the body - it gets wider too... and that forces the place that is 0.330" in diameter to be further up, ergo, the headspace gets longer.

 

[Turbulent Turtle]

I still don't see how that is possible while still respecting the 23 degree angle of the shoulder.

 

[bigedp51]

I still don't see how that is possible while still respecting the 23 degree angle of the shoulder.

It's not possible, if you increase the diameter of a headspace gauge does the headspace gauge get longer. Answer "NO"

If the bolt face is a fixed point and chamber shoulder is a fixed point and I make the chamber larger in diameter does the bolt face move or the shoulder of the chamber move. Answer "NO"

The point in my first comments were simply you have SAAMI chambers and you have military chambers. And the difference being military chambers are fatter and longer than SAMMI chambers. If both the SAAMI chamber and the military chamber both have the same headspace setting, the chamber diameter means nothing.

 

[Turbulent Turtle]

Understood. Thanks for the explanation.

And Merry Christmas.