Headspace Gauges

[Doublehelix]

Looking at getting a set of headspace gauges for an AR-15, and I notice that there are Rem .223 as well as 5.53 mm. Is there a difference?

 

[duffman0286]

Neck is slightly different 5.56 is slightly modified for improved extraction....but with that said my .223 gauges work in my ar15 ... but there is a difference and .223 Wyde as well

 

[Doublehelix]

Thanks. It sounds like the set of .223 gauges would work for me as well then.

 

[sloughfoot]

So much disinformation. I hate the internet. Spend the money on headspace gauges if it makes you happy, but .223, Wylde, and GI 5.56 chambers are identical as far as headspace.

In my opinion, the best way to verify the headspace of your rifle is to fire one round. Take that fired case and insert it into a Wilson case gauge. If it is between the lines, you are GTG.

And you will always be GTG. Because headspace is set by the barrel extension. Why else do you not have to buy a bolt with your barrel anymore?

 

[indyjohn]

So much disinformation. I hate the internet.

Your expectations are too high. It will take a minute but they'll figure it out.

 

[sloughfoot]

Your expectations are too high. It will take a minute but they'll figure it out.

John, I know you remember the days when we HAD to pay an extra $80 for a bolt to be included with our new barrels. Then the barrel guys realized that it was no longer an issue so we have been buying barrels without new bolts for like 20 years.

Now the young guys are insisting on spending money on headspace gauges.... I should have invested in headspace gauge companies.....

 

[indyjohn]

John, I know you remember the days when we HAD to pay an extra $80 for a bolt to be included with our new barrels. Then the barrel guys realized that it was no longer an issue so we have been buying barrels without new bolts for like 20 years.

Now the young guys are insisting on spending money on headspace gauges.... I should have invested in headspace gauge companies.....

You are correct, my friend.

And to my point, the young guys had no one to teach them. So, they will learn eventually.

 

[duffman0286]

John, I know you remember the days when we HAD to pay an extra $80 for a bolt to be included with our new barrels. Then the barrel guys realized that it was no longer an issue so we have been buying barrels without new bolts for like 20 years.

Now the young guys are insisting on spending money on headspace gauges.... I should have invested in headspace gauge companies.....

You always verify proper headspace on a build its even good practice on completed firearms new or used.... I understand the AR-15 Mil spec interchangeably (which in theory should interchange without issue) but that does not guarantee anything.... How often to we hear about quality control slipping (that's been a major issue with the US made AK's which are far more forgiving platforms) I strongly recommend researching what happens to a AR when headspacing is off (7075 aluminum can fragment but generally will tear) when a ar blows up its pretty nasty when compaired to alot of other firearms and that risk only increases when swap manufactures... Best to never assume a weapon will be headspaced properly i also would never recommend firing a new build will out first checking headspace (a case gauge is used to verify a weapon is still within safe ranges)

and here is a nice short video again explaining what i said earlier about all three chambers being different (i assume you where talking about the cases being nearly identical) most of the difference is in the neck/throat
[video]http://www.brownells.com/GunTech/Brownells-Tech-Tip-AR-15-5-56-223-223-Wylde/detail.htm?lid=16770[/video]

 

[Leo]

Headspace gauges really only check the case neck datum line to the bolt face. Checking the throat and leade is done other ways. I have 5.56 X 45 headspace gauges, from about 30 years ago. A lot of barrels have been through my hands since then. I have never replaced a barrel that was not in spec with a new bolt or an old one. My barrel buying is always top shelf barrels from top shelf suppliers. I still strip the bolt and check each one, mostly because I already have the gauges. My stuff runs.

At the range it is pretty common to see parts bin self built guns that do not work. These are usually assembled with the cheapest parts that can be found at gun shows and the internet. I wonder how reliable the head spacing is on those discount, cheapie barrels produced for the bottom tier buyers?

 

[sloughfoot]

It seems to me that any barrel manufacturer that ships a barrel, no matter the cost, with headspace beyond specs should be criminally prosecuted. There just is no reason for any AR barrel from 50 bucks to 500 bucks to be out of spec.

Having said that, even if headspace is off, there is absolutely NO WAY that the rifle can or will blow up. Another internet misinformation that I detest.

Look at the 30.06 versus the 308 cartridge. About 100 thousands difference in headspace right? Fire a 308 out of your 30.06 rifle. It is kind of a non-event. The case blows out to match the bigger and longer chamber dimensions. The shoulder disappears. That is all.

Lets say you have a wartime captured German K98 with a mismatched bolt. Lets say headspace is excessive. You fire a 8mm round out of it. The case is blown out to match the headspace. When you reload for THAT rifle, you only resize enough so that your reloads will chamber. You don't resize to spec. We been doing this for many years.

All of a sudden the internet commandos have declared too much headspace will get your rifle blown up.

Slamfires blow up rifles.

Using pistol powders mistakenly blow up rifles.

Barrel obstructions blow up rifles.

Excessive headspace cannot, ever, under any circumstance, blow up a rifle. No matter what type.

Think about it.... Has everybody forgotten about the process of fire forming wildcat cartridges? The parent case is fired in the wildcat chamber and it conforms to the new dimensions by that firing. It isn't complex and there is no fear of a rifle blowing up. The creator of the new case might even be drinking a beer during the process.

A few years ago, I purchased a 6mm AR Turbo match rifle. I loaded up 500 pieces of 6mm AR anno with 105 bthp ammo and shot it in matches. The difference in 6mm AR and 6MM turbo is about 50 thousandths in headspace. I shot many cleans in matches and had no worries about anything blowing up in my face. The fired cases were resized to the new dimension. Not a big deal.

 

[Leo]

.

 

[Leo]

Using pistol powders mistakenly blow up rifles.

I remember that one. I have seen a couple barrel restriction blow ups. And a Hirtenberger machine gun ammo in a tight match barrel M14 blowup.

Luckily I never had any of those issues when using my own stuff, or when I was pulling the trigger on other peoples firearms.

We saw a situation where a person was repeatedly trying to shoot brass that was just a little too long for his chamber. In all the jacking around and forcing things, there was an accidental discharge but it did not damage the rifle.

 

[sloughfoot]

I remember that one.

I remember you were there that day. He always maintained that he reloaded with Win 748 but I am convinced it was 25 grains of Win 231. He has since passed on but I still flinch at his memory.

It was a truly fearsome explosion that destroyed his AR.

 

[Grimmis]

I just recently assembled a 300 blk upper and never tested the head space. Shoots just fine

 

[duffman0286]

It seems to me that any barrel manufacturer that ships a barrel, no matter the cost, with headspace beyond specs should be criminally prosecuted. There just is no reason for any AR barrel from 50 bucks to 500 bucks to be out of spec.

Having said that, even if headspace is off, there is absolutely NO WAY that the rifle can or will blow up. Another internet misinformation that I detest.

Look at the 30.06 versus the 308 cartridge. About 100 thousands difference in headspace right? Fire a 308 out of your 30.06 rifle. It is kind of a non-event. The case blows out to match the bigger and longer chamber dimensions. The shoulder disappears. That is all.

Lets say you have a wartime captured German K98 with a mismatched bolt. Lets say headspace is excessive. You fire a 8mm round out of it. The case is blown out to match the headspace. When you reload for THAT rifle, you only resize enough so that your reloads will chamber. You don't resize to spec. We been doing this for many years.

All of a sudden the internet commandos have declared too much headspace will get your rifle blown up.

Slamfires blow up rifles.

Using pistol powders mistakenly blow up rifles.

Barrel obstructions blow up rifles.

Excessive headspace cannot, ever, under any circumstance, blow up a rifle. No matter what type.

Think about it.... Has everybody forgotten about the process of fire forming wildcat cartridges? The parent case is fired in the wildcat chamber and it conforms to the new dimensions by that firing. It isn't complex and there is no fear of a rifle blowing up. The creator of the new case might even be drinking a beer during the process.

A few years ago, I purchased a 6mm AR Turbo match rifle. I loaded up 500 pieces of 6mm AR anno with 105 bthp ammo and shot it in matches. The difference in 6mm AR and 6MM turbo is about 50 thousandths in headspace. I shot many cleans in matches and had no worries about anything blowing up in my face. The fired cases were resized to the new dimension. Not a big deal.

Improper head space creates a environment where were bad things can happen and the issue that arises with excessive headspace is this is a environment where cases can split... I don't care who you are and what you say case failure is bad and should always be considered unsafe (i will admit these failures are quite rare but that doesn't mean we throw caution to the wind) anytime gas is pushing towards the breech of a firearm bad things happen and if you have case failure it greatly increases the risk of injury... Does that mean a firearm with excessive headspace is going to blow up NO but it does increase the risk.... tight head-space is not something to look over ether increases the risk of striking a raised primer (assuming it safely makes its way to the chamber) but most commonly it may not always allow the bolt to fully lock in battery which increases the risk catastrophic failure .... with the ar the use of cam pin this helps prevent firing out of battery (not saving it cant happen) but in a lot of other weapons the AKM for example which has a floating firing pin and improperly tight headspace very much causes this problem

Not also forgetting how important proper head spacing is for proper extraction, preventing damage, excessive wear and so on
this
But i challenge you find me one publication stating that headspace is not important and we can completely ignore it... I have always learn with firearms its best to stay on the side of caution gun parts aren't cheap and medical bills are higher yet

 

[Doublehelix]

Sorry to open a can of worms. I appreciate all of the advice and the passionate comments.

First off, I am not a young guy, I am 57 and have been around for a long time. I am new to building ARs however, and do appreciate any and all advice. We are always learning, right?

Secondly, I did not ask *if* I should use a headspace gauge, I just asked about the differences between the .223 and the 5.56 gauges.

I appreciate you guys trying to save me from the evils of headspace checking, but it is something that I am interested in, and have the money, so why the rant? There are plenty (100's) of threads around the internet ranting back and forth on the *need* to check the headspace or not to check the headspace, there is no need to start another one. That was not my intent with my original post, so I am sorry if that is what I started.

As I said, I appreciate all of your wisdom and your many years of experience, but this is obviously a hot button question for you all as it appeared to set you guys off.

It may or may not be a necessary process as is being debated, but it is something that I want to do, and for $60 for a set of gauges, it is well worth the peace of mind, and I am learning something in the process about the AR15 system operation. It is all good! Deep breaths everyone!!!

 

[sloughfoot]

You are absolutely correct sir. I did hijack your thread. I apologize. Was your question answered? In short. there is no appreciable difference in 5.56 and .223 headspace gauges and since all dies size to .223 dimensions, and proper reloading demands bumping the shoulder .004 for your rifle ,it is a moot point. Of course, the two chambers are different, but headspace is the only thing measured by a headspace gauge. Not throat or leade.

It is just astounding to me that so many people have not heard of fire forming brass cases to a new dimension. It has been published in thousands of articles in hundreds of magazines over the last 100 years or so.

 

[Doublehelix]

You are absolutely correct sir. I did hijack your thread. I apologize. Was your question answered? In short. there is no appreciable difference in 5.56 and .223 headspace gauges and since all dies size to .223 dimensions, and proper reloading demands bumping the shoulder .004 for your rifle ,it is a moot point. Of course, the two chambers are different, but headspace is the only thing measured by a headspace gauge. Not throat or leade.

It is just astounding to me that so many people have not heard of fire forming brass cases to a new dimension. It has been published in thousands of articles in hundreds of magazines over the last 100 years or so.

No need to apologize, we are all on the same team here.

Yes, my question was answered, and TBH, I figured that this was the answer but wanted to make sure.