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Zero headspace is perfect


Alan Waters
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23 hours ago, Alan Waters said:

Speaking of .45 ACP. The headspace is changing every time it is sized. .45 and .38 Super brass gets shorter as it is sized. Unlike bottle neck cases which get longer.

There is some weird stuff that goes on with first firing :-). With my 6-284 the primer pockets get DEEPER on first firing of the brass. If I uniform the primer pockets in virgin brass, then fire form it (really the case body is not changing shape any to speak of with 6-284) the uniformer will never touch the bottom of the pocket again, does not do a good job cleaning the pocket. If I fire them first time without uniforming, then uniform, on every subsequent reload the uniformer cleans the pocket nice, and will even shave a little brass if you pull the powder measure handle a little too hard :-).

Have not seen that with any other cartridge.

 

The 357 AR which is made from 223 basic brass from starline (easiest way, people did use 223 brass before the 223 basic was avail) if you do not expand the body with a custom made expander that goes deep into the case they shorten up a whole bunch on first firing, which is not good because they headspace on the case mouth. 

Bill

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  • 4 months later...
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Very informative. I was thinking along the same lines as Alan while reading the first page, I'm glad that was explained better. 

Now what do you do if you have short headspace, other than reaming out the chamber?

My 308 Rainier Match barrel is a hair short, wont quite close on a 1.630 Clymer GO guage but chambers multiple different 168gr 308 rounds showing Sharpie marker wear on the ogive from touching the lands but nothing I can feel with my fingernail on the bullet itself. 

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  • 3 months later...
On 4/23/2019 at 5:13 AM, dubya said:

Very informative. I was thinking along the same lines as Alan while reading the first page, I'm glad that was explained better. 

Now what do you do if you have short headspace, other than reaming out the chamber?

My 308 Rainier Match barrel is a hair short, wont quite close on a 1.630 Clymer GO guage but chambers multiple different 168gr 308 rounds showing Sharpie marker wear on the ogive from touching the lands but nothing I can feel with my fingernail on the bullet itself. 

Before you get too carried away did you check your headspace with the ejector removed from the bolt?

If it still doesn't close with the ejector removed then the only way to alter it is with a chamber reamer. If it "won't quite close" then it is very very close, like within a thou or so, so very little will need to be done to fix it.

Simple job for any competent gunsmith.

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I have a question.   It just seems crazy how expensive headspace Go, No-Go, and Field gauges are, and sometimes they are even hard to find.  35 to 50 bucks seems to be the going rate, which to this poor boy, is nuts!

Now I know this is a really "redneck", "bubba" idea, but I'll stick my neck out and pose the question anyway.  Why couldn't you take a new brass case for whatever caliber/gun you are working with, and fill it with epoxy so that it is solid and can not deform.  (Couldn't crush or change the shoulder datum.)  Then glue a piece of brass shim stock or steel feeler gauge as mentioned by the original poster onto the base of the brass, of the appropriate thickness.  Presto; a $1.98 No-Go gauge.  Right?  No?

Kindly comments appreciated....

Vettepilot

 

 

 

Edited by Vettepilot
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2 hours ago, Vettepilot said:

I have a question.   It just seems crazy how expensive headspace Go, No-Go, and Field gauges are, and sometimes they are even hard to find.  35 to 50 bucks seems to be the going rate, which to this poor boy, is nuts!

Now I know this is a really "redneck", "bubba" idea, but I'll stick my neck out and pose the question anyway.  Why couldn't you take a new brass case for whatever caliber/gun you are working with, and fill it with epoxy so that it is solid and can not deform.  (Couldn't crush or change the shoulder datum.)  Then glue a piece of brass shim stock or steel feeler gauge as mentioned by the original poster onto the base of the brass, of the appropriate thickness.  Presto; a $1.98 No-Go gauge.  Right?  No?

Kindly comments appreciated....

Vettepilot

 

 

 

Buy a set of gauges, you only need a 'go' and a 'no go'.

Anything else is guess work.

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3 hours ago, Vettepilot said:

 35 to 50 bucks seems to be the going rate, which to this poor boy, is nuts!

What's your face worth, if the gun blows up in your face?...  Missing fingers, maybe -that's acceptable?...   Not for me...

Check out this .50 Cal from a shiit-manufacturer.  Wonder if he headspaced it first before firing?  Of course he didn't.  He spent the cheapest amount he could on the gun...

https://www.military.com/video/guns/rifles/50-cal-blows-up-in-shooters-face/3223685684001

Watch the embedded vid in that link...   :thumbup:

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On 8/12/2019 at 10:14 PM, Vettepilot said:

I have a question.   It just seems crazy how expensive headspace Go, No-Go, and Field gauges are, and sometimes they are even hard to find.  35 to 50 bucks seems to be the going rate, which to this poor boy, is nuts!

Now I know this is a really "redneck", "bubba" idea, but I'll stick my neck out and pose the question anyway.  Why couldn't you take a new brass case for whatever caliber/gun you are working with, and fill it with epoxy so that it is solid and can not deform.  (Couldn't crush or change the shoulder datum.)  Then glue a piece of brass shim stock or steel feeler gauge as mentioned by the original poster onto the base of the brass, of the appropriate thickness.  Presto; a $1.98 No-Go gauge.  Right?  No?

Kindly comments appreciated....

Vettepilot

 

 

 

I have used cases to create my own headspace gauge. Typically when I am doing a wildcat chamber for myself. I do cut the neck off using a case trimmer so I can be sure that the shoulder is what we are actually headspacing on not the case neck. Several times I had already bought 500-1000 cases of the same lot to use in the gun I was building.

That said we have no idea if the mfg made brass to spec or not, in my case I did not care because nobody makes factory ammunition anyway. In your case using a case of one mfg and lot number may not put you in a good place for that next box of ammo from Mao mart.

Bill

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  • 5 months later...
On 8/12/2019 at 9:14 PM, Vettepilot said:

I have a question.   It just seems crazy how expensive headspace Go, No-Go, and Field gauges are, and sometimes they are even hard to find.  35 to 50 bucks seems to be the going rate, which to this poor boy, is nuts!

Now I know this is a really "redneck", "bubba" idea, but I'll stick my neck out and pose the question anyway.  Why couldn't you take a new brass case for whatever caliber/gun you are working with, and fill it with epoxy so that it is solid and can not deform.  (Couldn't crush or change the shoulder datum.)  Then glue a piece of brass shim stock or steel feeler gauge as mentioned by the original poster onto the base of the brass, of the appropriate thickness.  Presto; a $1.98 No-Go gauge.  Right?  No?

Kindly comments appreciated....

Vettepilot

 

 

 

Wow... Please do not take this personally. The manner in which you asked this question sets off red flags. Your knowledge of headspace and the way different types of actions lockup and unlock before the cartridge is fired and after it is fired is very limited. Your going to get yourself hurt or worse yet someone else. This is very blunt.. you cannot check headspace on the first virgin shot out of any firearm with casings new or once fired. You have to know what your headspace is before you pull the trigger. There are different techniques using new or fired cases to check headspace, usually in the course of setting up reloading dies. There are other reason also, that I'm not going to get into.

Headspace gauges are Not Expensive or Hard to Obtain. A catastrophic failure is horrible. I've seen 3, they all required immediate medical attention to the face, eyes hands, and arms. All on semi-auto M1A's, exact cause unknown. On this forum it is understood were talking about building and fixing Semi-Auto's on the AR platforms.

This is how I know, you really do not understand headspace or how Semi-Autos unlock upon firing, and what happens when the trigger is pulled. Semi-Autos have a very violent cycle of operation. Once the round is fired, and that bolt starts to unlock, nothing is going to stop the cycle of operation. The kaboom happens when the bolt is maybe half way back, it then splits the aluminum receiver open like peeling a banana. Guess what.. that is where your face is. Listen and believe me,.... these rifle are not like a Bolt Rifle that lock up like a vault when you close the bolt. There is a nice picture of a catastrophic failure a few posts up from here, look at it and ponder for a few minutes.

You have received good advice by other members believe it. Buy yourself a set of headspace gauges GO and NO-GO for 308 Win and the 7.62x51 Nato if that is what your building, they are different.

If you buy a barrel online in today's world in REF to the AR platform in .308 or 223 you have no idea if you have a SAMMI chamber or a Nato chamber. I do not care what is stamped on the barrel, it can be stamped 308 Win and have a 7.62x51 chamber in it, they are two different animals. 

I offer this.. buy the gauges send me a PM, you can call me, we can talk for hours on the phone if necessary, about the proper way to use the gauges to measure headspace and why we use them. This knowledge will far exceed the cost of the gauges, This knowledge was priceless for me many years ago, when a gentleman named Boots Obermeyer (Obermeyer Rifled Barrels) took time out of his life to help me understand it in depth, and the reasons for doing so.

Regards

 

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  • 2 months later...
On 2/13/2020 at 1:27 AM, Anderson3754 said:

Wow... Please do not take this personally. The manner in which you asked this question sets off red flags. Your knowledge of headspace and the way different types of actions lockup and unlock before the cartridge is fired and after it is fired is very limited. Your going to get yourself hurt or worse yet someone else. This is very blunt.. you cannot check headspace on the first virgin shot out of any firearm with casings new or once fired. You have to know what your headspace is before you pull the trigger. There are different techniques using new or fired cases to check headspace, usually in the course of setting up reloading dies. There are other reason also, that I'm not going to get into.

Headspace gauges are Not Expensive or Hard to Obtain. A catastrophic failure is horrible. I've seen 3, they all required immediate medical attention to the face, eyes hands, and arms. All on semi-auto M1A's, exact cause unknown. On this forum it is understood were talking about building and fixing Semi-Auto's on the AR platforms.

This is how I know, you really do not understand headspace or how Semi-Autos unlock upon firing, and what happens when the trigger is pulled. Semi-Autos have a very violent cycle of operation. Once the round is fired, and that bolt starts to unlock, nothing is going to stop the cycle of operation. The kaboom happens when the bolt is maybe half way back, it then splits the aluminum receiver open like peeling a banana. Guess what.. that is where your face is. Listen and believe me,.... these rifle are not like a Bolt Rifle that lock up like a vault when you close the bolt. There is a nice picture of a catastrophic failure a few posts up from here, look at it and ponder for a few minutes.

You have received good advice by other members believe it. Buy yourself a set of headspace gauges GO and NO-GO for 308 Win and the 7.62x51 Nato if that is what your building, they are different.

If you buy a barrel online in today's world in REF to the AR platform in .308 or 223 you have no idea if you have a SAMMI chamber or a Nato chamber. I do not care what is stamped on the barrel, it can be stamped 308 Win and have a 7.62x51 chamber in it, they are two different animals. 

I offer this.. buy the gauges send me a PM, you can call me, we can talk for hours on the phone if necessary, about the proper way to use the gauges to measure headspace and why we use them. This knowledge will far exceed the cost of the gauges, This knowledge was priceless for me many years ago, when a gentleman named Boots Obermeyer (Obermeyer Rifled Barrels) took time out of his life to help me understand it in depth, and the reasons for doing so.

Regards

 

I second this, headspace gauges are of paramount importance. I can't even imagine how many people are out there today, assembling ARs from a market saturated with parts that just go together too easily...

I've seen this happen first hand, on a 5.56 small frame AR, home build. The guy brought the gun to the range where we were shooting after having just assembled it. I can't say for sure what the exact cause was, but something was out of spec: barrel nut loose, improper chamber, etc... 

I was down on the 100yd side, he was down on the 25yd. I watched him chamber the first round and the bolt wasn't closing right. He was messing and fighting with it and it caught my attention. It hit me, I thought: poop I better say something. Before I could get a word out, he finally got a round to chamber after popping the forward assist over and over. He threw the gun up on target and pow!! 

Looked like a frag going off in his face. I knew he was hurt, he was still in shock, standing there dazed holding the rifle in his left hand, right hand shaking and just starting to drip a good stream of blood. He says: What happened? I can't see anything... I told him to lay the rifle down pointing away from anyone. I took cover behind a berm til he kneeled and laid it down.

It shredded his firing hand pretty bad, looked like a hit from about a 20ga shotgun. It blew the bolt carrier sideways out of the ejection port. It blew the mag out of the lower and the spring, floorplate and live rounds just scattered. He took some shrapnel, to his right hand and a piece or two in his forehead. Damn he was lucky, to be honest. We got him out of there via ambulance. I will never forget it.

The moral here is, these rifles are WAY too easy to assemble. They are dangerous as hell if everything isn't built exactly right. Headspace gauges are a requirement in my opinion, I have a set for every cartridge I use. For the price of a box of ammo or two, they are worth every penny. With all the AR barrels and parts on the market, I know there's tons of parts out of spec out there. It's easy to get excited about a new build and rush into firing it. We all get it...

I will not fire a ANY firearm without it, period. Even if it's a factory new rifle, the tolerances are so small, they must be checked prior. Buy them, don't take that chance. Buy them from a reputable manufacturer too: Forster, Clymer, Manson... I own Forster and Manson. I'm sure there's many of us here, myself included, that would be more than happy to help you out like Anderson3754 has offered to do. Every round fired without checking headspace is pure luck. It also needs to be recorded, from prior to shot #1, through the life of the firearm. Because there are a myriad of ways it can change, a $30-$40 gauge beats a trip to the ER or worse, every time...

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  • 2 weeks later...
On 11/13/2018 at 11:04 PM, 308kiwi said:

Unfortunately not, it's the one drawback of gas operated rifles, the gas port will always move around the barrel diameter regardless of where you remove material to set the barrel back to correct excess head space.

I've spent many hours trying to figure a way to do this and haven't yet come up with one that will work, except you could remove exactly .0625" from the shoulder and the breech face, this will set the chamber back .0625 and realign the gas port at 12 o'clock and then you would re-cut the chamber with a reamer to the correct head space. But to try to do this to only set the chamber/head space back a few thou doesn't work.

This is right!  It would also adversely affect the alignment pin location on your Barrel extension.  You must do it in one complete turn (0.0625 in this example) and then re-cut the chamber.

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  • 2 months later...

Hate to revive something but I'm just trying to make sure I don't kill myself or someone else...

Build1 - M5 Aero 18" fluted SS - complete upper

Build2 - M5 Aero 18" CMV - complete upper

So... I went ahead and purchased a set of Forster .308 gauges (NOT NATO) - GO 1.630 / NOGO 1.634 / FIELD 1.638. Just for kicks Forster NATO measurements are - GO 1.6344 / NOGO 1.6455. 

Build1 - Using a Toolcraft BCG closed on GO - Would not close on NOGO - 👍

Build2 - Using same  Toolcraft BCG closed on GO - closed on NOGO - 😥 - would not close on .308 FIELD 🤔

Called Aero and got the typical blah, blah, blah - don't mix parts - blah, blah, blah. I didn't manufacture the barrel or BCG and as far as I can tell headspace between .308 and 7.62x51 were established before I was born... Anyhoo. Went ahead against better judgement and bought an Aero BCG. Guess what - same exact friggen results on Build2 with the Aero BCG.

Is the best road here to send the Build2 upper back to Aero with their friggen BCG or am I just being picky in wanting my headspace to be tighter than a fuking FIELD gauge? To make matters worse, Forster says that if you close on a NOGO gauge all is not lost. Just try a FIELD gauge and if it doesn't close you're probably A-OK...

Pissed

FYI - Extractor and plunger were removed on both BCG's prior to testing - barrels were dry as I didn't want any oil to take up a couple of hundred thou.

Edited by PaddyMac
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On 11/13/2018 at 11:45 PM, 98Z5V said:

I found that spec, years ago, in a military manual reference.  The 'net is so polluted with information now, that finding it is a fruitless waste of time.  I will find it again, someday, and save the shiit out of it when I do.  And post it here with an immediate request that it be pinned...  :thumbup:

Hey 98Z5V - Is this it?

Generally:
1.630 is the minimum acceptable
1.6335 was the minimum limit for production M14s (other vary)
1.634 is the maximum for new built match shooters
1.636 is the maximum for hunting
1.638 is the maximum for safe shooting (civilian liability)
1.6375 was the maximum new build limit for a new built M14 (others vary)
1.6415 is the maximum rework limit for M14s (others vary)
1.6455 is the reject threshold for M14s (others vary)

You will note that the listed "7.62" are really only for the M14.  The M40 and M24 sniper rifles have different headspace limits, as does the M110, you'll have to consult the depot level repair manual for those limits (you may have to ask Knight's Armament for the M110 specs).

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On 11/13/2018 at 9:38 PM, 98Z5V said:

And that torque should be 175 lb/ft.  Good luck finding that spec in a military manual.  It took me years to find that, and searching these days doesn't turn it up. 

 

6 minutes ago, PaddyMac said:

Hey 98Z5V - Is this it?

Generally:
1.630 is the minimum acceptable
1.6335 was the minimum limit for production M14s (other vary)
1.634 is the maximum for new built match shooters
1.636 is the maximum for hunting
1.638 is the maximum for safe shooting (civilian liability)
1.6375 was the maximum new build limit for a new built M14 (others vary)
1.6415 is the maximum rework limit for M14s (others vary)
1.6455 is the reject threshold for M14s (others vary)

You will note that the listed "7.62" are really only for the M14.  The M40 and M24 sniper rifles have different headspace limits, as does the M110, you'll have to consult the depot level repair manual for those limits (you may have to ask Knight's Armament for the M110 specs).

Nah, not headspace, man - I was referencing the barrel extension torque spec.  :thumbup:

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14 hours ago, PaddyMac said:

I sent Aero a message a few minutes ago to get their take on this. I'll call them later if I don't get a response.

Aero won't know - BA makes their barrels.  Getting Clint from BA on the phone is almost impossible, too.  The real-deal spec on barrel extension torque, at least militarily, is 175 lb/ft.  That extension should NEVER come off, unless you really mean it.

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