Which headspace gauge

[JackOfAllTrades]

I have an AR-15 I built up with a .223 Wylde chamber.

I played the odds and have fired it with .223 Remmington and it works. No obvious signs of overpressure or anything bad, but I would like to actually check the headspace rather than opperate on the "it hasn't blown up yet" method.

So which gauge to buy?

From what I have read the 5.56 NATO cartridge is derived from the .223 Remmington cartridge and the .223 Wylde chamber is derived from the 5.56 NATO chamber..

Supposedly the cases of 5.56 NATO and .223 Remmington cartridges are the same. It is the free bore that is different. I believe that the .223 Wylde chamber is somewhere between the two.

This leads me to believe that a headspace gauge for 5.56 NATO, .223 Remmington, and .223 Wylde should be the same since the headspace gauges don't involve the free bore at all.

Yet when I look at gauges, the dimensions are all over the map. No one seems to agree on what size they should be. 5.56 NATO gauges are clearly longer than .223 Remmington, and I have no idea what to make of few .223 Wylde gauges I have seen.

Since I want to shoot 5.56 NATO out of this rifle, I am thinking that the 5.56 gauges would be the way to go... working on the assumption that if it is safe to shoot .223 Remmington out of a 5.56 NATO chamber, so if it is safe for 5.56 it is safe for .223.

Or, I could go for the .223 Remmington gauges since they are the smaller of the gauges and if there isn't excessive headspace using those gauges, there isn't excessive headspace for 5.56... but what if there isn't enough headspace for 5.56.

I could go for one of each. Use the 5.56 Go gauge gauranteeing the "larger" 5.56 NATO cartrige will fit and the .223 Remmington No-Go gauge to make sure that there isn't excessive headspace for the more strict .223 Remmington cases. Of course if it failed with the .223 Remmington No-Go gauge it might still be good for 5.56 NATO...

Maybe I should just go with the 5.56 NATO gauges then...

I am open to opinions here...

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I found a post allegedly by Bill Wylde who says that the .223 Wylde chamber and 5.56 NATO share the same body dimensions. It is only the parts past the shoulder that are different.

If that is the case, then 5.56 NATO gauges look like the way to go.

 

[mac1911]

http://www.midwayusa.com/product/859123/ptg-headspace-go-gage-223-wylde

you would want a 223 wylde gauge.... seems it passes the go test already ? need a no go and a field for worn rifles?

more info than you may need but here is some http://ar15barrels.com/forming.shtml

 

[mac1911]

http://www.brownells.com/gunsmith-t.../5-56mm-maximum-headspace-gauge-prod6646.aspx

you could get this also ?

 

[dcmdon]

Buy a go gauge and convert it to a no-go gauge by simply putting a piece of scotch tape on the back. Its an old trick, but it works.

Remember one thing though. If you have a .223 wylde chamber, there should not be any problems with .223. If anything, it would be 5.56.

In order of dimensions it goes .223< Wylde< 5.56

So a .223 round is actually looser in a wylde chamber than in a .223 chamber.

 

[mac1911]

Bill Wylde designed the Wylde chamber for service rifle competition.
It covers the higher pressure the 5.56 NATO is loaded to along with being able to handle 80 grain match bullets.
Your SAMMI spec 223 remington was originally design for light short bullets.
So the throat/lead/free bore is smaller/tighter/shorter.

Think of it like this. From the point where the neck of the brass case ends is where the critical differences lie.
What Bill Wylde did was creatate a chamber that was safe for 5.56 NATO pressures yet yielded results of a "match" chamber.

What happens when you put a 5.56 NATO into a 223 remington chamber is the 5.56 55 and 62 grain bullets in general are a different profile and tended to get very close or even touching the lands.
With the 5.56 NAT0 loaded to high pressure ( to meet velocity requirement of mil spec. and to assure cycling in several platforms. ) if loaded into A 223 rem chamber and the bullet is touching the lands pressure increases even more. So you have 5.56 NATO at 62,000psi vs 223 rem running @ 55,000 psi roughly.

Bill Wylde created a chamber dimension that basically will shoot accurately and still be safe with NATO ammo and handle the longer heavier match bullets and still provide positive function in a AR.

 

[dcmdon]

So Mac, correct me if I'm wrong.

Since the Wylde chamber was developed to shoot long heavy bullets, a short 55-62 gr bullet will still have to jump longer to reach the lands with a 5.56 chamber than with a Wylde chamber.

Is that right?

So as far as the amount of Leade, the order from longest to shortest, is 5.56 --> Wylde --> .223 Remington

right?

 

[mac1911]

Something like that. In the links I posted there are drawings of each chamber.
When you start to compare the chambers you start to see where the differences are.
5.56 is on the larger side of measurements for function, reliable clambering and being able to shoot all the different variants of 5.56 military stuff from m855- armor piecing, tracers detect.
There are also different bullets and bullet profiles. For example: if you load a Hornady 55 grain FMJ BT to max mag length it's going to cram into the lands as it's a "fat" little bullet. From the tip it doesn't taper all that much vs something like the Sierra 80 grain match king. Which has a long thin tip.
There are other 223 chamberings also. For those most part to be safe you need headspace gauges for what ever your rifle is chambered for. Then you need to load appropriate charges and bullets.

I know if I had my old 223 rem bolt gun with 1/12 twist barrel if I tried loading a M855 or even a 68 grain match bullet it would not chamber , you would have to cram the bolt over.....this is where the danger lies.

 

[highscore]

Also, the .556 case doesn't hold as much powder because of wall thickness. You can reload them for .223 as long as they fit in your gage. Starting powder charge should be reduced a bit as pressure will be a bit higher. Just don't shoot .556 factory in a .223.

 

[jasons]

Don't worry about the chamber differences, they're not relevant to measuring head space. The 5.56 spec is a bit looser than .223. A military nogo is about the same (a tad bigger actually) as a civilian field. The go gauges are slightly different too but not enough to matter.

TL/DR: Just get the .223 gauges and you'll be in spec.

Edit: This is informative: http://www.ar15barrels.com/data/headspace.pdf

 

[JackOfAllTrades]

Ok, so here is how this saga turned out...

Since I want to shoot 5.56 out of this rifle, I purchased the 5.56 NATO gauges.

The bolt closes on the GO gauge and will not close on the NO-GO gauge.

I should be good to go with either 5.56 or .223

 

[mac1911]

yes