Headspace Gauge Check

darekzman

Four Pointer
I'm building my first AR and I'm close to being finished. Building two actually. Since all is "Mil Spec", I'm wondering if I need to check the headspace when I'm all finished. Does everyone do this? Is it necessary to buy one 'go' and one 'no-go' gauge? I found them for around $50 each. Both AR's are chambered in 223 Wylde. Hate to spend $100 on something I don't really need. Is it rare for this headspace check to fail the test? What does everyone else do post build? To bad my local gun shop doesn't have 223 Wylde gauges, otherwise I would have brought them in for a quick check. Thoughts from those more experienced?
 

LanceR

Six Pointer
Contributor
How rear something might be means nothing if you are the one it happens too. For you then, the possibility would be 100%....

If the headspace is too tight you will possibly have a failure to lock the bolt or a stuck cartridge case with, very likely, a broken extractor or torn case rim. If the headspace is too loose you will have a live grenade a few inches from you face when it goes off or, if you're lucky, a bunch of stretched and cracked cases.

So, yes, you need to check the headspace. Brownells has a video series on it and there are others all over the internet (but they may not be correct). You can buy or rent the gauges. Search for "headspace gauge rental" and you'll likely find them for rent.


Lance
 

darekzman

Four Pointer
Thanks LanceR, A live grenade a few inches from my face somehow doesn't sound that appealing. So now I'm looking for gauges and have found that some say you need gauges specifically marked as 223 Wylde while others say 5.56/223/223 Wylde are all exactly the same as far as gauges are concerned. Can't find a straight answer. And can't find anyone who has both the Go and No-Go gauge in stock for "223 Wylde". The chamber of the barrel of course is different among these three but are the gauges as well? Help!
 

LanceR

Six Pointer
Contributor
Dimensionally, the external dimensions of the 5.56x45mm NATO and the .223 Remington cartridges are the same. The difference is in the chamber dimensions. A quick check of the differences in chamber dimensions of the 5.56 NATO, .223 Wylde and .223 Remington shows that the difference is in the throat of the chamber with 5.56 being largest in diameter and the Remington the smallest.

You can shoot .223 Remington ammo in a 5.56mm or Wylde chamber safely. On the other hand, shooting 5.56mm ammo in a .223 Remington chamber can lead to excessive chamber pressure and in extreme cases to a bulged or burst chamber. The Wylde sits dimensionally between the 5.56mm and the Remington so it can handle either the 5.56mm or .223 Remington ammo and is intended to give a bit of an accuracy edge over the 5.56mm chamber.

Brownell's recommends using .223 Remington gauges for the Wylde and be sure that both are from the same manufacturer. They cost less than $30 each.....

http://www.brownells.com/GunTech/Brownells-Tech-Tip-AR-15-5-56-223-223-Wylde/detail.htm?lid=16770

It is worth noting that the case wall of the 5.56mm is thicker than the .223 Remington so if you reload military brass start with a grain less powder than the reloading manual shows and keep an eye out for signs of excessive pressure, especially when nearing maximum charges.


Lance
 

pinehunter

Eight Pointer
For the record you can measure your case volume by its water capacity. Fill a an empty case with water and weigh it. I have found NATO 7.72 brass to have less volume than .308 but not have not found the same to be true with 5.56 vs .223. Always err on the side of caution but I see a fair amount of the 5.56 vs .223 and have not seen any pressure signs that would indicate there is a real difference.
 

darekzman

Four Pointer
OK so the 223 Remington gauges are the same as 223 Wylde gauges. Got it. I'll have to order a set then. Thanks for the clarification.
 

darekzman

Four Pointer
Broke down and bought a set of Pacific Tool & Gauge 223 Rem Go/No-Go gauges off Amazon for $90. Thanks for all the info.
 
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